Antenna coil, and RFID-use tag using it, transponder-use antenna

ABSTRACT

An antenna coil includes an air-core coil wound helically in a plane and a plate magnetic core member inserted in the air-core coil to be approximately parallel with a plane of the air-core coil. The magnetic core member is formed by a soft magnetic metal, an amorphous or ferrite, or a composite member of a powder, flake and plastic, or rubber. The magnetic core member is formed by performing an injection molding operation or a compressing molding operation of the composite member. Alternatively, the magnetic core member is a magnetic coating formed by applying and drying the composite member. A non-magnetic conductive plate that has a conductivity is layered on a surface of the air-core coil through which the magnetic core member is inserted. The conductive plate is made of a copper, a copper alloy, an aluminum or an aluminum alloy having 0.01 to 2 mm thickness. The antenna coil is operated by relatively high frequency while it is rigid relatively.

This application is a 371 of PCT/JP02/09955 filed Sep. 26, 2002.

1. Technical Field

The present invention relates to an antenna coil which is used for anidentification tag in which an RFID (Radio Frequency Identification)technology or an EAS (Electronic Article Surveillance) technology isused.

Also, the present invention relates to an antenna which is used for atransponder such as a tag or a reader/writer in which the EAS technologyis used.

More specifically, the present invention relates to a transponderantenna which is provided with a helix coil so as to be attached to anarticle.

2. Background Art

Conventionally, for a tag in which the RFID technology or the EAStechnology is used, an identification tag is known to which an IC chipin which an information is stored and a condenser for resonation areconnected to an antenna coil electrically. In such an identificationtag, it has been know that the tag is activated by transmitting a radiowave having a predetermined frequency from a transmitting/receivingantenna in an interrogator to the antenna coil. Also, an article isidentified or monitored by reading the stored information in the IC chipaccording to a read-out command in a data communication by a radio waveor by detecting a resonation for a radio wave having a specificfrequency.

For a conventional antenna coil which is used for such an identificationtag, it has been known that a lead wire is wound helically around acenter of an axial line of a magnetic core member which is formed in ashaft manner. In a case in which an article to be controlled is a metalmember, such a tag in which an antenna coil is used is fixed on thearticle such that an electrically insulating spacer having 5 to 10 mmthickness is inserted between the antenna coil and the article so as toavoid undesirable influence by the metal article. However, in the aboveconventional antenna coil, a diameter of the magnetic core member isrelatively large, and an interval between the metal article and theantenna coil is relatively large. Therefore, there has been adisadvantage that the antenna coil protrudes excessively from thearticle which is an object to be controlled.

In order to solve such a disadvantage, an antenna coil which is formedby inserting a magnetic core member into an air-core coil which is woundhelically in a plane such that the magnetic core member should beapproximately parallel with the plane in the air-core coil (see JapaneseUnexamined Patent Application, First Publication No. 2000-48152). Themagnetic core member in such an antenna coil is made of an amorphoussheet or a electromagnetic steel plate. The thickness of the antennacoil can be as thin as possible by inserting the magnetic core member soas to be approximately parallel with a plane in the air-core coil.Simultaneously, a magnetic flux is transmitted through the magnetic coremember such that a direction of the magnetic flux should be parallelwith a plane of the article to which the antenna coil is attached. Thus,the thickness of the space which is inserted between the antenna coiland the article may be thin; therefore, more protrusion of the antennacoil from the article which is an object to be controlled can be reducedthan in a conventional case.

However, in the antenna coil in the above Japanese Unexamined PatentApplication, First Publication No. 2000-48152, the magnetic core memberis made of an amorphous sheet or an electromagnetic steel plate.Therefore, A Q-value which can be used if a frequency is nearly 100 kHzmay be obtained. However, if the frequency of the radio wave is as highas several MHz to several ten MHz, there has been a disadvantage in thatan eddy current occurs in the amorphous sheet or the electromagneticsteel plate in the magnetic core member; thus, the Q value decreased.Particularly, in recent years, a tag has been realized for actual use inwhich an RFID technology is used which is activated by the frequencysuch as 3.56 MHz. There was a disadvantage in that an antenna coildisclosed in Japanese Unexamined Patent Application, First PublicationNo. 2000-48152 could not be used for a tag which is activated by a highfrequency radio wave.

On the other hand, a sintered ferrite has been known conventionally fora magnetic core member which can be used for a high frequency radiowave. However, the sintered ferrite is fragile relatively. Inparticular, if a sintered ferrite which is formed very thinly so as tobe used for a magnetic core member so as to form a thin antenna coil,there may occur a crack on such a magnetic core member; thus, there is aproblem in that an actually operable condition may be limited. Incontrast, if relatively a thick sintered ferrite plate is used for amagnetic core member so as to enhance the rigidity, the thickness of theantenna coil increases. Therefore, there is a problem in that it is notpossible to realize an object to reduce a protrusion of the antenna coilfrom an article which is an object to be controlled.

Furthermore, there has been other requirement below in the conventionaltechnology.

Conventionally, an antenna coil which is used for an identification taghas been known such as an antenna coil which is made by winding a leadwire of which surface is coated by an insulating layer around anapproximate square and attaching on a base plate or by forming anapproximate coil main body 2 by removing an unnecessary part from aconductive layer such as an aluminum film or a copper film which islayered on the base plate 1 according to an etching method or a punchingmethod as shown in FIG. 24.

However, in an antenna coil shown in FIG. 24, a magnetic flux isgenerated in a vertical direction which passes through the base plate 1as indicated by an arrow in the drawing. If such an antenna coilcontacts a metal article, a radio wave which is transmitted toward theantenna coil passes through the base plate 1 and further through themetal article. Therefore, an eddy current is generated on a metal partdue to the magnetic flux which passes therethrough; thus, the eddycurrent generates an undesirable influence. Therefore, there was aproblem in that the antenna coil may not be operated properly. Also,even if the antenna coil can be operated, the loss therein increases;thus, there was a problem in that an operable distance of the antennacoil may be shortened to a great extent.

In order to solve such a problem, as shown in FIG. 23, an antenna coilhas been known which comprises a magnetic core member 6 which has aplate shape or a cylindrical shape and a conductive member 7 which iswound around the magnetic core member 6 helically. In the antenna coilwhich is shown in FIG. 23, a magnetic flux is generated in an axial coredirection of the magnetic core member 6 as indicated by an arrow in thedrawing. Therefore, if the antenna coil is attached to a metal article,a radio wave which is transmitted toward the antenna coil does not passthrough the metal article. Thus, a desirable operation in the antennacoil has been anticipated.

However, the antenna coil shown in FIG. 23 is produced by winding aconductive member 7 around an outer surface of the magnetic core member6. Such a process for winding a conductive member 7 takes times andeffort; thus, there has been a disadvantage from a productivity point ofview. Also, an entire antenna coil may be relative thick because theconductive member 7 is wound around the magnetic core member 6. If suchan antenna coil is attached on a surface of an article, there has been aproblem in that the antenna coil protrudes from the article to a greatextent relatively.

Also, there has been other requirement in the conventional technologybelow.

Conventionally, an antenna coil which is used for an identification taghas been known such as an antenna coil which is made by winding a leadwire of which surface is coated by an insulating layer around anapproximate square and attaching on a base plate or by forming anapproximate coil main body 2 by removing an unnecessary part from aconductive layer such as an aluminum film or a copper film which islayered on the base plate 1 according to an etching method as shown inFIG. 24.

Also, other antenna coil has been known which comprises a magnetic coremember 6 which is formed in a plate shape or a cylindrical shape and aconductive member 7 which is wound around the magnetic core member 6helically.

On the other hand, in the antenna coil shown in FIG. 23, a magnetic fluxis generated in an axial core direction of the magnetic core member 6 asindicated by an arrow in the drawing. Therefore, if the antenna coil isattached to a metal article, a radio wave which is transmitted towardthe antenna coil does not pass through the metal article. Thus, adesirable operation in the antenna coil has been anticipated. However,the antenna coil which is shown in FIG. 23 is produced by winding theconductive member 7 around an outer surface of the magnetic core member6. Therefore, there has been a disadvantage in that such a process forwinding a conductive member 7 is complicated relatively. Also, an entireantenna coil may be thick relatively; thus, there has been a problem inthat the antenna coil may protrude from the article if the antenna coilis attached on a surface of the article.

On the other hand, there were requirements in a conventionaltransponder. Conventionally, a transponder has been known whichcomprises an antenna and an IC chip which is connected electrically tothe antenna so as to store an information for an article which is anobject to be controlled. Also, a transponder which comprises an antennaand a condenser which is connected to the antenna electrically has beenknown. In a transponder in which an IC chip is connected to the antenna,data which are stored in the IC chip is read out according to a read-outcommand in a radio wave data communication such that the transponder isactivated by transmitting a radio wave having a predetermined frequencyfrom a transmitting/receiving antenna from an interrogator to theantenna, or a read-out operation and writing in operation for data areperformed such that the data are written in the IC chip according to thewrite in command. For a case in which an entering/exiting operationcontrol is performed, such a transponder can perform various informationcontrol such as identifying an individual person, and storing times forentrance and exit. Also, for a case in which a manufacturing process iscontrolled, the transponder can exchange various information such as aninstructing for processing a product, storing the process, andcontrolling a result of product inspection.

On the other hand, the transponder in which a condenser is connected toan antenna has a specific resonating frequency. The transponder emits aradio wave by resonating with a radio wave having a predeterminedfrequency which is transmitted from the interrogator such that it isidentified whether or not the interrogator is a transponder which has apredetermined frequency by the radio wave. Such a transponder cannotexchange as various information as the transponder which has an IC chip.However, such a transponder has an advantage such as a simple structure.For example, such a transponder can be used for measuring how manypeople enter/exit a room if such a transponder is used for roomenter/exit controlling operation. If such a transponder is used for aproduct manufacturing process, it is possible to measure a quantity ofproducts which pass therethrough. Here, if transponders having differentresonating frequencies are used, it is possible to measure the quantityof products for a plurality of classified variations. For example, it ispossible to measure the number of people based on male-or-female base,or adult/child base separately. If such a transponder is attached to acommercial commodities in a commercial store, it is possible to monitora taken-out commodity by disposing an interrogator at an exit. By doingthis, there is a case in which a transponder is used such that it ispossible to prevent an illegal taken-out of the commercial commodities.

These antennae which are used for a conventional transponder are formedby winding a lead wire of which surface is coated by an insulating layeraround an approximate square helically so as to be attached on a baseplate or by performing an etching operation or a punching operation forremoving an unnecessary part of a conductive layer such as an aluminumwhich is layered on the base plate or a copper layer in a helicalmanner. Such a transponder which has an antenna was fixed on an articleby screws etc. so as to avoid an undesirable influence from an object tobe controlled which is made of a metal member under condition anelectrically insulating spacer having 5 to 10 mm thickness is insertedbetween the transponder and the object.

However, such a space is relatively thick in the above conventionaltransponder. Therefore, an interval between the metal article and thetransponder is relatively large even if the antenna can be formed thin.Thus, there has been a disadvantage in that the transponder protrudefrom an article which is an object to be controlled to a great extent.Therefore, there was a concern that the transponder may contact variousmembers therearound while the article is transported.

DISCLOSURE OF INVENTION

An object of the present invention is to provide an antenna coil havingrelatively high rigidity which can be used in a relatively highfrequency.

Other object of the present invention is to provide an antenna coil inwhich a space which should be inserted between the antenna coil and anarticle is unnecessary such that a protrusion of the antenna coil froman article which is an object to be controlled can be more reduced thanthe conventional antenna coil.

In addition, an object of the present invention is to provide a tagantenna coil which can be formed quite thinly so as to be operatedreliably while contacting the metal article closely. Also, an object ofthe present invention is to provide a tag antenna coil which is suitablefor a mass production.

Furthermore, other object of the present invention is to provide a tagantenna coil and an RFID tag using the tag antenna coil of whichthickness is maintained thinly while contacting a metal article closely.Also, an object of the present invention is to provide a tag antennacoil and an RFID tag using the tag antenna coil which are suitable for amass production.

Also, other object of the present invention is to provide an antenna fora transponder which can be attached to any material condition of asurface directly of an article which is an object to be controlledwithout using a spacer.

An invention according to a first aspect of the present patentapplication is an improvement for an antenna coil comprising an air-corecoil 12 which is formed by a coil member which is wound on a plane, anda magnetic core member 13 which is inserted in the air-core coil 12 soas to be approximately parallel to the plane in the air-core coil 12.

Its characteristic feature is that the magnetic core member 13 is formedby a composite member of a soft magnetic metal member, a powder of anamorphous member or a powder of a ferrite member or a flake member and aplastic member or a rubber.

In the antenna coil according to a first aspect of the presentinvention, the magnetic core member 13 is formed by a composite materialmember; thus, such a magnetic core member 13 is more rigid than amagnetic core member which is formed by a fragile sintered-ferrite.Therefore, it is possible to obtain a rigidity for the antenna coil byusing the magnetic core member 13 which is formed by a composite member.

Also, a soft magnetic metal member, an amorphous member, or a ferrite inthe composite member are dispersed in a plastic member or a rubber so asto be insulated from each other. Therefore, a magnetic core member 13which is a composite member is not a conductive member. Therefore, aneddy current is not generated even if the magnetic core member 13receives a high frequency radio wave. Therefore, a Q value neverdecreases due to the eddy current even if a radio wave has relatively ahigh frequency; thus, it is possible to realize an antenna coil whichcan be used sufficiently reliably in a relatively high frequency radiowave.

An invention according to a second aspect of the present patentapplication is an antenna coil the magnetic core member 13 which isformed by ejecting the composite member, or compressing the compositemember, or re-shaping a flat rolled composite member.

In the antenna coil which is disclosed in the second aspect of thepresent patent application, it is possible to form the magnetic coremember 13 by the composite member. Thus, it is possible to reduce aprotrusion from an article by forming a thin magnetic core member 13.

An invention according to a third aspect of the present patentapplication is an antenna coil in which the magnetic core member 13 isformed by a magnetic coating which is formed by drying the compositeafter applying the composite.

In the antenna coil according to the third aspect of the present patentapplication, it is possible to obtain a magnetic core member 13 having0.8 mm or thinner thickness which is difficult to form in an ejectionmolding operation and a compressing molding operation. Thus, it ispossible to form quite a thin antenna coil. Therefore, it is possible torestrict a protrusion of the antenna coil which is attached on thearticle from the article to a great extent.

An invention according to a fourth aspect of the present patentapplication is an improvement for an antenna coil which comprises anair-core coil 12 which is formed by a coil member which is wound on aplane, and a magnetic core member 13 which is inserted in the air-corecoil 12 so as to be approximately parallel to the plane in the air-corecoil 12.

Its characteristic feature is that a non-magnetic conductive plate 14 islayered on a surface of the air-core coil 12 through which the magneticcore member 13 is inserted.

In the antenna coil which is disclosed in the fourth aspect of thepresent patent application, an eddy current is not generated on asurface to which the article is attached under condition that an antennacoils is attached onto the metal article such that the conductive plate14 is disposed between the article and the air-core coil 12 and a radiowave is transmitted; therefore, the conductive plate 14 blocks the radiowave which passes through the air-core coil 12 so as not to pass throughthe article. As a result, a spacer which has been inserted between theantenna coil and the article conventionally is unnecessary; thus, it ispossible to activate the antenna coil reliably. Here, in the antennacoil according to the fourth aspect, the magnetic core member 13 isformed by an amorphous sheet or an electromagnetic steel plate which isoperable even if the air-core coil 12 is operated by a relatively lowfrequency.

An invention according to a fifth aspect of the present patentapplication is an antenna coil in which the conductive plate 14 isformed by a copper, a copper alloy, an aluminum, or an aluminum alloy.

In the antenna coil which is disclosed in the fifth aspect of thepresent patent application, it is possible to obtain a conductive plate14 which can block the transmission of the radio wave through thearticle reliably.

An invention according to a sixth aspect of the present patentapplication is an antenna coil the conductive plate 14 has 0.01 to 2 mmthickness.

In the antenna coil which is disclosed in the sixth aspect of thepresent patent application, an antenna coil which includes theconductive plate 14 can be formed quite thinly; therefore, theprotrusion from the article is restricted even if the article is formedby a metal member; thus, it is possible to prevent the antenna coil fromcontacting various members therearound while transporting the article.

As shown in FIGS. 4 and 5, an invention according to a seventh aspect ofthe present patent application is an antenna coil which comprises aninsulating member 111 which is formed by an electrically insulating filmor an electrically insulating sheet, a continuous conductive member 112which has forwarding sections 112 a and returning sections 112 b whichare formed alternatively so as to wind on a surface of the insulatingmember 111, a first magnetic core member 113 which is bonded on a backsurface of the insulating member 111 so as to cover the forwardingsection 112 b from the back surface of the insulating member 111 withoutoverlapping the forwarding section 1112 a.

In the antenna coil which is disclosed in the seventh aspect of thepresent patent application, the first magnetic core member 113 is bondedto a back surface of the insulating member 111; therefore, the magneticflux which is generated by an electric current which passes theconductive member 112 passes the first magnetic core member 113 so as toshape a loop which is indicated in a true-line arrow in FIG. 4 so as tobe parallel with a surface of the article 18. Even if a surface of thearticle to which the antenna coil is attached is a metal member, theantenna coil operates reliably without receiving an undesirableinfluence from the metal member.

Also, the first magnetic core member 113 is bonded onto a back surfaceof the insulating member 111 so as to cover the conductive member 112 bfrom a back of the insulating member 111 without overlapping theforwarding sections 112 a. Therefore, as shown by a dotted arrow in FIG.4 in an enlarged manner, the magnetic flux which passes through thefirst magnetic core member 113 passes above the forwarding sections 112a while a part of the magnetic flux disperses in an end section there.The magnetic flux returns back to the neighboring first magnetic coremember 113 again such that a continuous conductive member 112 whichincludes the forwarding sections 112 a and the 112 b forms the antennacoil which is wound around a part of the magnetic flux.

An invention according to an eighth aspect of the present patentapplication is an antenna coil as shown in FIGS. 6 and 7 in which asecond magnetic core member 114 covers the forwarding section 112 a soas not to overlap the returning section 112 b on the surface of theinsulating member 111 such that an end section of the second magneticcore member 114 is bonded so as to overlap an end section of the firstneighboring magnetic member 113, and the second magnetic core member 114introduces a magnetic flux which passes through the first magnetic coremember 113 onto a surface of the insulating member 111 on the forwardingsection 112 a.

In the antenna coil according to the eighth aspect of the present patentapplication, the magnetic flux which passes through the first magneticcore member 113 passes through the first magnetic core member 113 andthe second magnetic core member 114 while moving the first magnetic coremember 113 and the second magnetic core member 114 alternatively asshown by a true-line arrow in FIG. 6. Therefore, the forwarding sections112 a and the 112 b exist on a top surface and a back surface of themagnetic flux. The continuous conductive member 112 which includes theforwarding sections 112 a and the conductive member 112 b form theantenna coil unitarily which is wound around the magnetic flux. As aresult of this, it is possible to obtain an antenna coil 10 which hasthe same characteristics as a conventional antenna coil which has beenproduced by winding a lead wire around a magnetic core member relativelyeasily. Thus, it is possible to improve productivity in a massproduction better than a case for the conventional antenna coil whichhas been produced by winding a lead wire therearound.

An invention according to a ninth aspect of the present patentapplication is an antenna coil in which a plurality of conductive lines21, 22 are disposed so as to wind on a surface of the insulating member111 in a predetermined interval along with each other in the continuousconductive member 112, and an end section of the conductive line 21 isconnected to a starting end section of the neighboring conductive line22 as shown in FIGS. 8 and 9.

In the antenna coil which is described in the ninth aspect of thepresent patent application, the quantity of forwarding sections 21 a and22 a and returning sections 21 b and 22 b which exist alternatively on atop surface and a back surface of the magnetic flux which passes throughthe first magnetic core member 113 and the second magnetic core member114 are increased; thus, it is possible to increase so-called a turningnumber easily. By increasing the turning number, it is possible toimprove the characteristics in the antenna coil.

An invention according to a tenth aspect of the present patentapplication is an antenna coil in which the continuous conductive member112 is formed on a surface of the insulating member 111 by etching aconductive film which is bonded on an entire surface of the insulatingmember 111 in a predetermined pattern, or performing a screen printingoperation or a vapor deposition operation of the conductive member on asurface of the insulating member 111 in a predetermined pattern.

In the antenna coil which is described in the tenth aspect of thepresent patent application, it is possible to form the conductive member112 on a surface of the insulating member 111 relatively easily; thus,it is possible to improve the productivity for the antenna coilfurthermore.

An invention according to an eleventh aspect of the present patentapplication is an antenna coil in which either one or both of the firstmagnetic core member 113 or the magnetic core member 114 is formed by asoft magnetic metal member, a powder or a flake which is formed by anamorphous member or a ferrite member, a plastic composite member, aplate or a film which is formed by a soft magnetic metal member, anamorphous film or its layered member, or a ferrite member.

In the antenna coil which is described in the eleventh aspect of thepresent patent application, the first magnetic core member 113 or thesecond magnetic core member 114 is relatively thin. By forming the firstmagnetic core member 113 and the second magnetic core member 114 whichform an entire part in a thickness direction of the antenna coil thinly,it is possible to form an entire antenna coil thinly.

An invention according to twelfth aspect of the present patentapplication is an antenna coil in which either one or both of the firstmagnetic core member 113 and the magnetic core member 114 is formed by amagnetic coating which is formed by applying an ink or an applyingmember which include a magnetic powder onto the insulating member 111and drying the ink or the applying member.

In the antenna coil which is described in the twelfth aspect of thepresent patent application, it is possible to obtain the magnetic coremembers 13 and 114 having a thickness such as 0.8 mm or thinner which isdifficult to form in an injection molding operation. Thus, it ispossible to form the thickness of the antenna coil very thinly.Therefore, it is possible to restrict the protrusion of the antenna coilfrom the article when the antenna coil is attached onto the article verymuch.

An invention according to a thirteenth aspect of the present patent isan antenna coil in which a conductive member 116 made of a sheet memberor a plate member is bonded onto a back surface of the insulating member111 so as to cover the first magnetic core member 113.

In the antenna coil which is described in the thirteenth aspect of thepresent patent application, the conductive member 116 is disposedbetween the conductive member 12 and the article; therefore, theconductive member 16 blocks the transmission of the radio wave towardthe article. Therefore, there is not generated a loss due to an eddycurrent etc. which is generated on a surface of the metal member even ifa surface of the article is formed by a metal member. As a result, it ispossible to operate the antenna coil reliably.

An invention according to a fourteenth aspect of the present patentapplication is a tag antenna coil which comprises a coil main body 21 awhich is formed by a conductive coil member 211 which is wound in aplane, and a magnetic core member 213 made of a sheet member or a platemember which is bonded on a surface of the coil main body 211 a suchthat an end 213 a of the magnetic core member 213 is disposed in acentral section 211 b which is surrounded by the coil main body 211 aand another end 213 b of the magnetic core member 213 is disposed at anoutside of the coil main body 211 a so as to cross a part of the coilmain body 21 a as shown in FIGS. 11 and 12.

In the tag antenna coil which is described in the fourteen aspect of thepresent patent application, the magnetic core member 213 is bonded so asto be across a part of the coil main body 211 a; therefore, it ispossible to enhance the Q value of the antenna coil. Also, the magneticflux which is generated by an electric current which passes the coilmain body 211 a which is formed by the conductive coil member 211 passesthrough its magnetic core member 213 so as to shape a loop which isshown by a true-line arrow in FIG. 11. Therefore, the direction of themagnetic flux is parallel with a surface of the article; thus, an eddycurrent which is generated on a metal member of a surface of the articleis restricted even if the tag antenna coil is attached onto a surface ofthe article which is formed by a metal member. Thus, the antenna coil isoperated reliably.

An invention according to a fifteenth aspect of the present patentapplication is a tag antenna coil in which the coil main body 211 a isformed by punching a conductive plate or a conductive film.

In the tag antenna coil according to the fifteenth aspect of the presentpatent application, it is possible to form the coil main body 211 aeasily; thus, it is possible to improve the productivity for the antennacoil.

An invention according to a sixteenth aspect of the present patentapplication is a tag antenna coil in which the coil main body is formedby etching a conductive film which is bonded on an entire main surfaceof an electrically insulating film or a sheet 212 in a predeterminedpattern, or performing a screen printing operation or a vapor depositionoperation of the conductive member on an entire main surface of theelectrically insulating film or the sheet 212 in a predeterminedpattern.

In the tag antenna coil according to the sixteenth aspect of the presentpatent application, the conductive coil member 211 is disposed on anelectrically insulating film 212 or a sheet; therefore, it is possibleto handle it easily. Therefore, it is possible to obtain an antenna coilby an easy operation such as only layering and attaching the magneticcore member 213 onto another main surface of a film or a sheet 212.Thus, it is possible to improve the productivity in a mass productionwith compared to a case for a conventional antenna coil which is shownin FIG. 23 in which a lead wire is wound around an outer surface of amagnetic core member.

An invention according to a seventeenth aspect of the present patentapplication is a tag antenna coil in which the magnetic core member 213is a magnetic coating which is formed by applying a soft magnetic metalmember, a powder or a flake which is formed by an amorphous member or aferrite member, a plastic composite member, a plate or a film which isformed by a soft magnetic metal member, an amorphous film or its layeredmember, or a ferrite member, or an ink or an applying member whichinclude a magnetic powder onto an electrically insulating film or asheet and drying the ink or the applying member.

In the tag antenna coil according to the seventeenth aspect of thepresent patent application, the magnetic core member 213 is relativelythin. Thus, it is possible to form an entire antenna coil thinly byforming the magnetic core member 213 thinly which occupies a most partof the antenna coil in a thickness direction.

An invention according to an eighteenth aspect of the present patentapplication is a tag antenna coil in which the magnetic core member 213is a magnetic coating which is formed by applying an ink or an applyingmember which include a magnetic powder onto another main surface of theelectrically insulating film or a sheet 212 and drying the ink or theapplying member.

In the tag antenna coil according to the eighteenth aspect of thepresent patent application, it is possible to obtain the magnetic coremember 213 having 0.8 mm or thinner thickness which is difficult to formin the injection molding operation and a compressing molding operation.Therefore, it is possible to form the antenna coil with a very thinthickness. Also, it is possible to restrict the protrusion of theantenna coil from the article very much when the antenna coil isattached onto the article.

An invention according to a nineteenth aspect of the present patentapplication is a tag antenna coil in which a conductive member 216 madeof a sheet member or a plate member is bonded onto a surface of the coilmain body 211 a so as to cover the magnetic core member 213.

In the tag antenna coil according to the nineteenth aspect of thepresent patent application, its conductive member 216 is disposedbetween the coil main body 211 a which is formed by the conductive coilmember 211 and the article; therefore, the conductive member 216 block atransmission of the radio wave toward the article. Therefore, theantenna coil can be operated reliably without generating a loss due toan eddy current which is generated on a metal surface even if a surfaceof the article is formed by a metal member.

An invention according to a twentieth aspect of the present patentapplication is an RFID tag which comprises an antenna coil 10 which isattached to an article 18, and an IC chip which is connected to theantenna coil 10 electrically such that a specific information for eacharticle 18 is stored in the IC chip, such that the antenna coil 10 isattached to the article such that the magnetic core member 213 isdisposed between the article 18 and the coil main body 211 a.

In the RFID tag according to the twentieth aspect of the present patentapplication, the magnetic flux which is generated by an electric currentwhich passes the coil main body 211 a passes mainly through the magneticcore member 13 when the magnetic core member 213 is disposed so as toneighbor the article 18; thus, few magnetic flux passes through thearticle 18. Therefore, the antenna coil 10 hardly receive itsundesirable influence with regardless to whether or not the article 18is a metal member. Thus, the RFID tag in which the antenna coil 10 isused is operated reliably.

An invention according to a twenty-first aspect of the present patentapplication is an improvement of a transponder antenna as shown in FIGS.15 and 16 which is connected to an IC chip 313 or a condenserelectrically so as to be attached to an article 311.

Its feature is that it comprises a conductive plate member 314 a ofwhich back surface is attached to the article 311, a coil main body 314b which is wound helically on a surface of the conductive member 314 avia an insulating member 316 and fixed thereon such that a turningnumber and a coil diameter are adjusted so as to realize a predeterminedcharacteristic value under a wound condition.

In the transponder antenna according to the twenty-first aspect of thepresent patent application, the coil main body 314 b is adjusted so asto obtain a predetermined characteristics value under condition that thecoil main body 314 b is wound around an outer surface of the conductiveplate member 314 a. Therefore, if an IC chip is connected to the antennain the transponder, it is possible to activate the transponder 12reliably by transmitting a radio wave having a predetermined frequencyfrom a transmitting/receiving antenna in an interrogator which is notshown in the drawing to the antenna 314. If a condenser is connected tothe antenna in the transponder, it is possible to resonate with theradio wave which is transmitted from the interrogator reliably. Also, inthe antenna 314, the coil main body 314 b is wound around an outersurface of the conductive plate member 314 a in advance; thus, apredetermined characteristic value is obtained. Therefore, if theantenna 314 is attached to a metal article directly which is an objectto be controlled, the coil main body 314 b does not receive anundesirable influence from the metal article; therefore, thecharacteristic value in the coil main body 314 b does not vary to agreat extent. Therefore, a space which has been necessary for attachingthe antenna 314 to the metal article is not necessary; thus, it ispossible to prevent the transponder 12 from protruding from the articlewhich is an object to be controlled to a great extent.

For a shape of the conductive plate member 314 a, it is possible to namea sheet, a plate, a helical member both end of which are connected suchthat an electric resistance per 1 cm width and 1 cm length is 5Ω orless.

Also, as shown in FIG. 15 in an enlarged manner, for a material for theinsulating member 316, non-conductive material is preferable such as asheet, a plate, or a film which is formed by a polyethylene member or apolyethylene terephthalate member.

In such a case, it is acceptable if the conductive plate member 314 amay be a conductive coating which is made by applying a conductive inkonto a back surface of such a insulating member 316 and drying thereof.Also, it is acceptable if the conductive plate member 314 a may be aconductive plating layer or a conductive vapor deposition layer such asa Cu or Al which are made by layering on a back surface of theinsulating member 316. In such a case, it is preferable that aninsulating member 316 having 0.01 to 5 mm thickness be used such that aninterval between the conductive plate member 314 a and the coil mainbody 314 b should be 0.01 to 5 mm.

Furthermore, as shown in FIG. 17, it is possible to form a hole 314 c ina section which is surrounded by the coil main body 314 b in theconductive plate member 314 a. As shown in FIG. 19, it is possible todispose a soft magnetic member 26 between the conductive plate member314 a and the coil main body 314 b. In a case in which a hole 314 c isformed on the conductive plate member 314 a which is in a central partof the coil main body 314 b, if an eddy current is generated in theconductive plate member 314 a due to a radio wave which passes throughthe coil main body 314 b, such an eddy current is generated in a narrowrange which neighbors the coil main body 314 b because of the hole 314c; thus, it is possible to restrict a decrease in the Q value in thecoil main body 314 b. On the other hand, if the soft magnetic member 26is disposed between the conductive plate member 314 a and the coil mainbody 314 b, the coil main body 314 b is electrically separated from theconductive plate member 314 a by the soft magnetic member 26; thus, theQ value in the coil main body 314 b improves. Therefore, it is possibleto adjust the turning number or the turning diameter of the coil mainbody 314 b relatively easily so as to obtain a predeterminedcharacteristic value.

An invention according to twenty-second aspect of the present patentapplication is an improvement for a transponder antenna as shown in FIG.20 which is connected to an IC chip 313 or a condenser electrically soas to be attached to the article 311.

Its characteristic feature is that the transponder antenna comprises aflat pate soft magnetic member 26 of which back surface is attached ontothe article 311 and a coil main body 314 b of which turning number andturning diameter are adjusted such that a predetermined characteristicvalue can be obtained under condition that it is wound around a surfaceof the soft magnetic member 26 so as to be fixed therearound.

In the transponder antenna according to the twenty-second aspect of thepresent patent application, when a radio wave is transmitted undercondition that an antenna 314 is attached onto the article 311 which ismade by a metal member, the soft magnetic member 26 blocks the radiowave so as not to pass toward the metal part; thus, an eddy current isnot generated in such a metal part. As a result, even if the article 311is formed by a metal member, a space which has been necessary is notnecessary. Therefore, it is possible to prevent the antenna 314 fromcontacting the members therearound while transporting the article 41.

Here, it is preferable that a product of a transmission rate of the softmagnetic member 26 and a thickness represented in a unit such as mmindicates 0.5 or larger. Also, it is preferable that the soft magneticmember 26 is formed by any one of members such as an amorphous alloy, aPermalloy, a magnetic steel, a silicon steel, a sendust alloy, a quenchsolidified member for Fe—Al alloy or a soft magnetic ferrite, a castedmember, a rolled strip member, a forged member, or a sintered member.Also, it is preferable that the soft magnetic member 26 is a coating ofa powder of a soft magnetic metal member or a soft magnetic ferrite, orcomposite member of a flake, a plastic member, or a rubber, or aapplying member of a powder of a soft magnetic metal member or a powderof a soft magnetic ferrite, or a flake. Furthermore, it is acceptable ifthe soft magnetic member 26 is a sheet which is formed by bonding aplurality of flakes which are made of a soft magnetic metal member or asoft magnetic ferrite onto a surface of a plastic base sheet such thatthe flakes contact closely each other. Also, it is acceptable if thesoft magnetic member 26 is a sheet which is formed by bonding aplurality of flakes which are made of a soft magnetic metal member or asoft magnetic ferrite onto a surface of a plastic base sheet such thatthe flakes contact closely each other, covering the flakes by a plasticcover sheet, and attaching the base sheet and the cover sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an antenna coil according to the present patentapplication.

FIG. 2 is a cross section of FIG. 1 so as to describe the condition inwhich the antenna coil is attached onto an article.

FIG. 3 is a plan view for an air-core coil in the antenna coil.

FIG. 4 is a cross section viewed in a line A—A shown in FIG. 5 so as todescribe an antenna coil according to a third embodiment of the presentpatent application.

FIG. 5 is a plan view for an antenna coil.

FIG. 6 is a cross section which corresponds to the FIG. 4 in which anantenna coil according to a fourth embodiment of the present patentapplication is shown.

FIG. 7 is a plan view for an antenna coil.

FIG. 8 is a cross section which corresponds to the FIG. 4 in which anantenna coil according to a third embodiment of the present patentapplication is shown.

FIG. 9 is a plan view for an antenna coil.

FIG. 10 is a plan view for an antenna coil which has a conductive memberwhich comprises three conductive lead wires.

FIG. 11 is a cross section viewed in a line A—A shown in FIG. 12 whichshows an antenna coil according to a fifth embodiment of the presentpatent application.

FIG. 12 is a plan view for an antenna coil.

FIG. 13 is a cross section which corresponds to the FIG. 11 in which anantenna coil according to a sixth embodiment of the present patentapplication is shown.

FIG. 14 is a plan view for an antenna coil.

FIG. 15 is a plan view for a transponder which includes an antennaaccording to a seventh embodiment of the present invention.

FIG. 16 is a cross section viewed in a line A—A in FIG. 15.

FIG. 17 is a plan view which corresponds to FIG. 15 which describes atransponder which includes an antenna in which a hole is formed in itsconductive member.

FIG. 18 is a cross section which corresponds to FIG. 16 which describesan antenna.

FIG. 19 is a cross section which corresponds to FIG. 16 which shows anantenna according to a second embodiment in which a soft magnetic memberis disposed.

FIG. 20 is a cross section which corresponds to FIG. 16 which shows anantenna according to a ninth embodiment in which the soft magneticmember is attached to an article.

FIG. 21 is a plan view which corresponds to FIG. 15 which shows a casein which a coil main body has a rectangular shape.

FIG. 22 is a view showing a condition for confirming operations in atransponder in the embodiments.

FIG. 23 is an isometric view for showing a conventional antenna coilwhich has a conductive member which is wound around an magnetic coremember helically.

FIG. 24 is an isometric view for showing a conventional antenna coilwhich comprises a helical coil section.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention are explained with referenceto drawings below.

As shown in FIGS. 1 and 2, an antenna coil 10 according to the presentinvention comprises an air-core coil 12 which is formed by winding aconductive member 11 c helically in a plane and a flat plate magneticcore member 13 which is inserted into the air-core coil 12 so as to beapproximately parallel with a plane in the air-core coil 12. Theair-core coil 12 is formed by winding a coated lead wire which forms theconductive member 11 c or by punching or etching a conductive plate in apredetermined pattern. Also, the air-core coil 12 can be formed byetching a copper film which is layered on an electrically insulatingfilm or a sheet or by performing a screen printing operation or a vapordeposition operation for a conductive member on a main surface of anelectrically insulating film or a sheet. In such a case, it is necessaryto form a hole such as a hole in a doughnut through which a magneticcore member 13 should be inserted in a central part of the air-core coil12 on an electrically insulating film or a sheet.

For a representative example, a case in which a air-core coil 12 isformed by etching a copper layer which is layered on an electricallyinsulating film 12 a is explained. First, a film 12 a which has copperfilms on both surfaces of the of the film 12 a is prepared. As shown inFIG. 3, a first through hole 12 b is formed near a central part of thefilm 12 a. A second through hole 12 c is formed near an outer marginalsection of a film near the first through hole 12 b. After that, ananti-etching paint is printed on both surfaces of the film 12 a by asilk screen method. The anti-etching paint is applied on a surface ofthe film 12 a in a rectangular helical manner such that a circumferencesof the first through hole 12 b and the second through hole 12 c, and thefirst through hole 12 b should be inner ends and an outer end should bedisposed near the second through hole 12 c. Consequently, a wide paintsection is formed on an outer end of the coil. In addition, ananti-etching paint is applied so as to be dried on another surface ofthe film 12 a such that the first through hole 12 b and the secondthrough hole 12 c communicate therebetween. Consequently, a copper filmon which a paint is not applied is removed by an etching operation;thus, a copper film on a section on which an anti-etching paint isapplied remains on the film 12 a.

After that, the anti-etching paint is removed from the copper film whichremains on the film 12 a. Also, a first terminal 11 a and a secondterminal 11 b around the first through hole 12 b and the second throughhole 12 c, a helical coil section 111 c in a rectangular coil mannerhaving an inner end such as a first terminal 11 a, and an intermediateterminal 11 d which is formed by a wide section on an outer end of thecoil section 11 c are formed on a surface of the film 12 a by aremaining copper film. In addition, a connective conductive member 11 ewhich connects the first through hole 12 b and the second through hole12 c on another surface of the film 12 a by the remaining copper film.After that, inner surfaces of the first through hole 12 b and the secondthrough hole 12 c are plated. The first terminal 11 a and the connectiveconductive member 11 e are connected. The second terminal 11 b and theconnective conductive member 11 e are connected. Thus, the firstterminal 11 a and the second terminal 11 b are connected electricallyvia the connective conductive member 11 e. After that, a hole 12 dthrough which the magnetic core member 13 is inserted is formed by apressing operation; thus, an air-core coil 12 is obtained. In such anair-core coil 12 which is obtained by etching a copper film which islayered on the electrically insulating film 12 a, it is possible to forma tag by connecting an IC or a condenser between the second terminal 11b and the intermediate terminal 11 d.

Referring back to FIGS. 1 and 2, the magnetic core member 13 is formedby a composite member. The composite member is formed by a soft magneticmetal member, an amorphous or a ferrite powder or a flake, or a plasticmember or a rubber. For such a soft magnetic metal member, it ispreferable to use a carbonyl iron powder or a reduced iron powderbecause a fine powder can be obtained easily. The reduced iron powdercan be obtained by performing a low-temperature reduction operation fora fine iron oxide in a hydrogen gas. Also, for such a soft magneticmetal member, it is acceptable if an iron, Permalloy, and amorphouspowder which are produced according to an atomizing method be used.Also, it is acceptable if an amorphous alloy flake be used which isformed by crushing a soft magnetic metal powder which is obtained by anatomizing method by using a crushing device or a ball-end mill andcolliding a powder and a melt alloy grain which are mechanicallyflattened onto a surface of a copper which is cooled by a water.

On the other hand, it is preferable to use an insulating resin such asan acrylic member, a polyester, a polyvinyl chloride, a polyethylene, apolystyrene, and an epoxy for such a plastic member. Also, it ispossible to use any synthetic rubber such as a natural rubber and abutyl rubber for a rubber.

For a method for producing a composite member, a method is appropriatein which a mixture of a soft magnetic metal member, a powder of anamorphous member or a powder of a ferrite member or a flake member and aplastic member or a rubber is kneaded so as to form a pellet for formingin a predetermined shape by an injection molding operation or acompressing molding operation. When the magnetic core member 13 isformed in an injection molding operation or a compressing moldingoperation, a flat plate stage section 13 a can be formed in the magneticcore member 13 unitarily with the air-core coil 12 as shown in FIG. 2simultaneously with its molding. Thus, it is possible to obtain arelatively thin antenna coil 10 relatively easily. In such a case, amagnetic field is established in a magnetic direction when the abovemixture is injected or compressed so as to dispose the soft magneticmetal members in arrays, the characteristics for the antenna coil 10 maybe improved further. Also, it is acceptable if the above mixture may beflattened by a roll so as to be slits, compressed to be deformed, orcasted in a mold. In any of the above cases, the characteristics areimproved by disposing the soft magnetic metal members in arrays byestablishing a magnetic field.

When a soft magnetic metal member or an amorphous powder are used, it ispreferable that its diameter should be in a range of 0.6 to 100 μm. Morepreferably, it should be in a range of 1 to 43 μm.

If the soft magnetic metal member or the amorphous are flakes, itsthickness should preferably be in a range of 0.1 to 10 μm. Morepreferably, its thickness should be in a range of 0.3 to 5 μm. If thediameter of the soft magnetic metal member or the amorphous powder issmaller than the above ranges, the powder intends to be oxidized moreeasily. If it is larger than the above ranges, there is a problem inthat a loss due to an eddy current increases. For a mixture ratio of thecomposite member, 10 to 95% of the amorphous or the ferrite should bepreferable. More preferably, it should be 40 to 90%. The rest of theratio indicates a plastic or a rubber. If the soft magnetic metalmember, the amorphous, or the ferrite are contained less than the aboverange, there is a problem that a magnetic permeability is too low. Ifthe soft magnetic metal member, the amorphous, or the ferrite arecontained more than the above range, the soft magnetic metal member, theamorphous, or the ferrite contact with each other; thus, the magneticcore member 13 may be conductive; therefore, there is a concern that theloss increases.

On the other hand, a non-magnetic conductive plate 14 is layered on asurface of the air-core coil 12 through which the magnetic core member13 is inserted. The conductive plate 14 is made of a copper, a copperalloy, or an aluminum, or an aluminum alloy so as to be bonded on asurface of the air-core coil 12 through which the magnetic core member13 is inserted. The conductive plate 14 is disposed between the air-corecoil 12 and the article 16 so as to seal the air-core coil 12 from thearticle 16 electro-magnetically. Thickness of the conductive plate 14 is0.01 to 2 mm. If the thickness of the conductive plate 14 is smallerthan 0.01, an essential effect such as electromagnetic sealing cannot beanticipated. If the thickness of the conductive plate 14 exceeds 2 mm,an interval between the article 16 and the air-core coil 12 mayincrease; thus, there is a disadvantage that the air-core coil 12 mayprotrude from the article 16 to a great extent.

In the antenna coil 10 which is formed as above, the magnetic coremember 13 is formed by a composite member. Therefore, the antenna coil10 is more rigid with compared to a magnetic core member which is formedby a fragile ferrite-sintered-member. Therefore, it is possible toobtain a rigidity in the antenna coil by using the magnetic core member13. Also, the soft magnetic metal member, the amorphous or the ferriteare dispersed in a plastic or a rubber and insulated from each other.Therefore, an entire magnetic core member 13 is not conductive; thus, aneddy current is not generated even if it receives a high frequency radiowave. Therefore, even if a frequency of a radio wave which is emittedfrom a transmitting antenna which is not shown in the drawing isrelatively high such as several MHz to several ten MHz, the Q value doesnot decrease due to the generated eddy current. As a result, the antennacoil 10 of the present invention is relatively rigid. Compatibly, it ispossible to use the antenna coil 10 sufficiently in a relatively highfrequency.

In particular, in the present embodiment, the non-magnetic conductiveplate 14 is layered on a surface of the air-core coil 12 through whichthe magnetic core member 13 is inserted; therefore, if the air-core coil12 is attached onto the article 16 via the conductive plate 14, theconductive plate 14 is disposed between an attaching surface of thearticle 16 and the air-core coil 12. Therefore, the air-core coil 12 isblocked from the article 16 electrically; thus, it is possible toprevent the self-inductance in the air-core coil 12 from varying and theQ value from decreasing perfectly. In particular, it is effective for acase in which the article 16 is formed by a ferromagnetic member. Thisis because of following reasons. That is, if the above conductive plate14 is bonded onto the air-core coil 12 which faces to the attachingsurface of the article 16 which is made of a ferromagnetic member, themagnetic flux which is about to pass through the article 16 among themagnetic flux which is emitted from the magnetic core member 13 passesabove the conductive plate 14 which has a high conductivity. Also, theconductive plate 14 is a non-magnetic member; therefore, there is veryfew hysteresis loss; thus, very few eddy current is generated. Thus, thearticle 16 which is made of a ferromagnetic member does not affect theair-core coil 12 undesirably.

Here, in the above embodiment, an example is shown in which the magneticcore member 13 is formed by performing an injection molding operation ora compressing molding operation, or a flattening molding operation forthe composite member. It is acceptable if the magnetic core member 13may be formed by applying and drying the composite member. In such acase, it is preferable to apply and dry the composite member on aninsulating resin film or a sheet which are not shown in the drawing.Here, it is preferable that the thickness of the insulating resin filmor the sheet should by 100 to 200 μm when the magnetic coating isformed. More preferably, it should be 30 to 150 μm. Also, the thicknessof the formed magnetic coating should be 10 to 800 μm. More preferably,it should be 30 to 300 μm. Here, if it is not possible to obtain apredetermined thickness in a single applying operation for a paint, itis possible to obtain a desirable thickness of coating by applying anddrying the same paint repeatedly. By doing this, the rigidity for themagnetic core member is obtained by an insulating resin film or a sheetif a magnetic core member which is made of a magnetic coating is formedon a surface of the insulating resin film or the sheet. Simultaneously,it is possible to obtain a magnetic core member 13 which having 0.8 mmthickness or thinner which is difficult to form in an injection moldingoperation. Furthermore, it is possible to obtain a thin antenna coil 10.

Next, examples of the present invention are explained with reference toa comparative example in detail below.

EXAMPLE 1

First, an air-core coil is formed on a main surface of an electricallyinsulating film. For the electrically insulating film, a polyimide filmhaving 50 mm longitude and 50 mm latitude and 50 μm thickness is used. Acopper film having 35 μm thickness is layered to be bonded on a mainsurface of the polyimide film so as to etch the copper film. By doingthis, an air-core coil which is wound helically in a four-timerectangular manner is formed on a main surface of the polyimide film.The conductive member which forms the air-core coil is formed so as tohave 0.8 mm width. An outer shape of the air-core coil is formed so asto have a dimension such as 18 mm×47 mm.

Next, a mixture of 92 weight % of a carbonyl iron powder and a nylonresin is injected into a mold. By doing this, a magnetic core member 13which is formed by a composite member having 0.87 mm thickness and 35mm×52 mm dimension is obtained. Consequently, a hole having 35 mm×1 mmof dimension is formed on an electrically insulating film which isdisposed in a center of the air-core coil. The magnetic core member 13is inserted into the hole so as to be approximately parallel with aplane of the air-core coil; thus, an antenna coil is obtained. Acomparative example 1 is an antenna coil which has a magnetic coremember which is obtained by injecting the composite member into a mold.

EXAMPLE 2

An air-core coil which is the same as that of the example 1 is formed onan electrically insulating film which is the same as the electricallyinsulating film of the example 1 by the same conductive member as thatof the example 1 by the process which is the same as the process in theexample 1. Also, a paint is prepared in which 70 weight % of amorphousflake, 10 weight % of acrylic resin, and 20 weight % of ethyl acetate asa solvent are mixed. The paint is applied and dried on an entire mainsurface of a film which is formed by a polyethylene terephthalate having0.1 mm thickness. Thus, a magnetic coating having 0.1 mm thickness isobtained. A film on entire main surface of which the magnetic coating isformed is cut in to a dimension of 35 mm×60 mm with the magneticcoating. Thus, the magnetic core member 13 which is made of a magneticcoating which is formed by applying and drying the composite member isobtained. Consequently, a hole having 35 mm×1 mm of dimension is formedon an electrically insulating film which is disposed in a center of theair-core coil. The magnetic core member 13 is inserted into the hole soas to be approximately parallel with a plane of the air-core coil; thus,an antenna coil is obtained. An example 2 is an antenna coil which has amagnetic core member which is formed by the magnetic coating.

COMPARATIVE EXAMPLE 1

An air-core coil which is the same as that of the example 1 is formed onan electrically insulating film which is the same as the electricallyinsulating film of the example 1 by the same conductive member as thatof the example 1 by the process which is the same as the process in theexample 1. Also, a magnetic core member which is formed by a layeredmember of an amorphous film having 4 layers of amorphous films having 10mm×60 mm of dimension and 20 μm thickness is prepared. Consequently, ahole having 35 mm×1 mm of dimension is formed on an electricallyinsulating film which is disposed in a center of the air-core coil. Themagnetic core member 13 is inserted into the hole so as to beapproximately parallel with a plane of the air-core coil; thus, anantenna coil is obtained. A comparative example 1 is an antenna coilwhich has a magnetic core member which is formed by the layered Memberof the amorphous film.

<Comparative Test>

Measurement terminals in a measurement device (Model 4396 commerciallyavailable under trade mark which is registered by HEWLETT PACKARD) formeasuring characteristics in a coil are connected to both ends of theair-core coil in the antenna coils in the examples 1 and 2, and acomparative example. An L value and Q value in the air-core coils aremeasured respectively which correspond to the predetermined frequency bythe measurement device.

Also, an aluminum plate as an article is prepared which has 100 mm×100mm dimension and 0.16 mm thickness. IC chips are connected to theair-core coils in the comparative example 1 and examples 1 to 3respectively so as to form tags which can be operated by a frequency of13.56 MHz by the IC chips and the antenna coil. It is confirmed whetheror not the tags are operated if the tags are disposed on surfaces of thealuminum plate respectively. The result is shown in a TABLE 1.

TABLE 1 Example 1 Example 2 Example 3 Magnetic Core Member CompositeMagnetic Amorphous Predetermined Member Coating Film Frequency L L L(MHz) (μH) Q (μH) Q (μH) Q 1 1.556 9.1 1.405 8.1 1.886 5.4 2 1.535 16.01.385 13.8 1.771 6.0 3 1.527 21.4 1.376 17.8 1.696 6.6 4 1.524 26.21.371 20.8 0.164 6.6 5 1.525 30.8 1.367 23.2 1.665 6.6 6 1.526 34.91.368 25.1 1.576 6.7 7 1.529 38.1 1.368 26.4 1.550 6.6 8 1.532 41.31.367 27.8 1.533 6.6 9 1.538 44.5 1.379 28.3 1.517 6.6 10 1.543 47.01.374 30.1 1.502 6.7 11 1.549 49.3 1.379 31.1 1.490 6.7 12 1.558 52.21.304 31.7 1.483 6.7 13 1.567 53.9 1.389 31.9 1.476 6.7 14 1.576 55.61.396 32.6 1.470 6.8 15 1.587 57.6 1.403 32.6 1.467 6.7 20 1.654 61.61.445 32.1 1.404 6.7 Confirmation Operated Operated Operated ofOperation

As understood from the TABLE 1, it is understood that the Q value isimproved by comparing the Examples 1 and 2 to the comparative example 1.The reason for this is estimated that the magnetic core member is anamorphous film in the comparative example 1; thus, an eddy current isgenerated on the magnetic core member. On the other hand, in theexamples 1 and 2, it is estimated that the magnetic core member isformed by a composite member; therefore, an eddy current is notgenerated on the magnetic core member. Also, the tag in which theantenna coils of the examples 1 and 2 are connected to the IC chip canbe operated even if the tag is disposed on a surface antenna coil of thecomparative example 1 does not operate. It is also estimated that thisis because the L value in the antenna coil of the comparative example 1varies according to whether or not the eddy current is generated; thus,the resonation frequency varies and the energy is absorbed; thus, a lossis generated.

Next, a second embodiment of the present invention is explained withreference to drawings.

As shown in FIGS. 4 and 5, the antenna coil 10 comprises an insulatingmember 111 which is formed by an electrically insulating film or anelectrically insulating sheet, a conductive member 112 which is formedby a conductive member to wind on a surface of the insulating member111, and a first magnetic core member 113 which is bonded on a backsurface of the insulating member 111. The insulating member 111 isformed in a rectangular shape by an electrically insulating plastic filmor a sheet, or a paper. It is preferable that the insulating member 111should be formed by a plastic film or a plastic sheet such as apolyester or a polyimide. The conductive member 112 can be formed on asurface of the insulating member 111 by etching a conductive film whichis bonded on a surface of the insulating member 111, bonding aconductive film which is punched in a predetermined pattern or a thinplate on a surface of the insulating member 111, or performing a screenprinting operation or a vapor deposition operation of the conductivemember such as Cu, Al, Zn on a surface of the insulating member 111 in apredetermined pattern.

As shown in FIG. 5, forwarding sections 112 a and returning sections 112b which extend in a longitudinal direction are formed alternatively soas to have a predetermined interval in its width direction on a surfaceof the insulating member 111 in the insulating member 111. Also, theconductive member 112 has a plurality of connecting sections 112 c whichconnect the both ends of the forwarding sections 112 a and the returningsections 112 b alternatively so as to wind the forwarding sections 112 aand the returning sections 112 b. Also, a pair of lead sections 112 d,112 d are formed on a surface of the insulating member 111. Ends of theconductive member 112 d are connected to the forwarding sections 112 aand the returning sections 112 b respective which are positioned in awidth direction on both ends of the insulating member 111. The otherends are disposed so as to be near an approximate center in a widthdirection of the insulating member 111 with each other. The IC chip andthe condenser 19 are bonded onto a surface of the insulating member 111under condition that the IC chip and the condenser 19 are connected toother ends of a pair of lead sections 112 d, 112 d electricallyrespectively.

On the other hand, the first magnetic core member 113 is bonded on aback surface of the insulating member 111 so as to cover the returningsections 112 b from a back surface of the insulating member 111 withoutoverlapping the forwarding sections 112 a. It is possible to form thefirst magnetic core member 113 by a soft magnetic metal member, or acomposite member which is formed by a powder or a flake and a plasticwhich are formed by a soft magnetic metal member, an amorphous member ora ferrite member. Also, it is acceptable if the first magnetic coremember 113 may be formed by an amorphous film or its layered member suchas an Fe amorphous alloy (METGLAS 2605-2 commercially available under atrademark of Alliedchemical corp.) and a Co amorphous alloy (METGLAS2712A commercially available under a trademark of Alliedchemical corp.)or a ferrite which is formed in a square manner.

It is possible to use a thermoplastic plastic member having a desirableformability or a thermoplastic plastic having a desirable heatresistance for a plastic in a composite member. For the above softmagnetic metal powder, an atomized powder such as a carbonyl iron powderand an iron-Permalloy, and a reduced iron powder etc. can be used. Onthe other hand, for a soft magnetic metal flake, a flake which is formedby molding a powder which is crushed by a ball-end mill etc. andflattening the powder mechanically and a flake which is formed bycolliding a melt grain of iron or a cobalt amorphous alloy to awater-cooled copper are used.

Also, if the first magnetic core member 113 is formed by a compositemember, it is possible to form the first magnetic core member 113 byperforming an injection molding operation or a compressing moldingoperation of the composite member. The first magnetic core member 113which is formed in this way is rigid with compared to a magnetic coremember which is formed by a fragile ferrite. Therefore, it is hardlybroken even if it is thin. Also, a powder or a flake which is formed bya soft magnetic metal member, an amorphous or ferrite is dispersed in aplastic so as to be insulated by the plastic with each other. Therefore,it is not conductive entirely. Thus, it is possible to obtain the firstmagnetic core member 113 which does not generate an eddy current even ifit receives a high frequency radio wave. Here, it is preferable to formthe first magnetic core member 113 as thin as possible which occupies amost of it section in a thickness direction of the antenna coil 10 asthin as possible. More specifically, in a case in which a sheet firstmagnetic core member 113 is used, it is preferable that the thickness ofthe sheet which forms the first magnetic core member 113 should be 0.01to 1 mm. More preferably, it should be 0.05 to 1 mm. Also, if a thinsheet is formed in this way, it is possible to adjust its thickness byforming the first magnetic core member 113 by layering a plurality ofsheets.

For a first magnetic core member 113 which is shown in FIGS. 4 and 5, asheet member which is formed by injected a composite member in a squaremanner is used. The first magnetic core member 113 is bonded on a backsurface of the electrically insulating member 111. The first magneticcore member 113 is bonded to the electrically insulating member 111 byapplying a bond to at least the first magnetic core member 113 or theelectrically insulating member 111 and putting the first magnetic coremember 113 onto the electrically insulating member 111. In such a case,the first magnetic core member 113 is bonded onto a back surface of theelectrically insulating member 11 so as to cover the returning sections112 b from a back of the electrically insulating member 111 withoutoverlapping the forwarding sections 112 a.

In this embodiment, as shown in FIG. 4, the sheet or plate conductivemember 116 is layered so as to be bonded on a back surface of theelectrically insulating member 111 so as to cover the first magneticcore member 113. The first magnetic core member 113 is formed by aconductive member such as a copper or an aluminum. If the first magneticcore member 113 has a conductivity, the conductive member 116 is layeredso as to be bonded such that an insulating film should be disposedtherebetween. It is preferable that the thickness of the conductivemember 116 should be 0.01 to 5 mm. By forming the conductive member 116with a thickness 0.01 to 5 mm, the interval between the conductivemember 116 and the conductive member 112 increases; thus, it is possibleto improve the characteristics of the antenna coil by improving the Qvalue in the conductive member 112. Also, it is preferable that anelectric resistance in an area of 1 cm width and 1 cm length in theconductive member 116 should be 5Ω or less.

The thickness of the antenna coil 10 which is formed in this way can bevery thin. Also, because of the thin thickness, even if the antenna coilis attached to the article 18, it hardly occurs that the antenna coil 10protrude from the article 18. Also, the first magnetic core member 113is bonded on a back surface of the electrically insulating member 111,the magnetic flux which is generated by an electric current which passesin the conductive member 112 passes through the first magnetic coremember 113 such that a loop can be formed as indicated by a true-linearrow in FIG. 4. Also, the first magnetic core member 113 is bonded on aback surface of the electrically insulating member 111 so as to coverthe returning sections 112 b from a back surface of the electricallyinsulating member 111 without overlapping the forwarding sections 112 a.Therefore, as shown by a dotted-line arrow in FIG. 4 in an enlargedmanner, a part of the magnetic flux which passes through the firstmagnetic core member 113 is dispersed on its end section so as to passabove the forwarding sections 112 a so as to return to the neighboringfirst magnetic core member 113.

Therefore, even if the tag antenna coil 10 is attached on a surface ofthe article 18, its magnetic flux direction is parallel with a surfaceof the article 18 as indicated by an arrow shown in FIG. 4; therefore,it hardly occurs that the magnetic flux passes through the article 18.Therefore, even if the article 18 is formed by a metal member, an eddycurrent which is generated in the article 18 is restricted; thus, theresonation frequency of the antenna coil 10 is not affected by the abovemetal article. Thus, the antenna coil 10 is operated reliably. Inparticular, in this embodiment, the conductive member 116 is layered soas to be bonded on a back surface of the electrically insulating member111 so as to cover the first magnetic core member 113; therefore, itsconductive member 16 is disposed between the first magnetic core member113 and the article 18. Therefore, the magnetic flux which passesthrough the first magnetic core member 113 so as to disperse from itsend section and pass above the forwarding sections 112 a increases;thus, the antenna coil 10 is operated reliably.

Here, in the above embodiment, explanations are made for the firstmagnetic core member 113 which is formed by a soft magnetic metalmember, a composite member, or a plate, a film made of the soft magneticmetal member, an amorphous film or its layered member, or a ferrite.However, it is acceptable if the first magnetic core member 113 maycomprise an insulating resin film or sheet which are not shown in thedrawing and a magnetic coating which is formed on a surface of aninsulating resin film or a sheet. Here, it is preferable that thethickness of the insulating resin film or a sheet is 10 to 100 μm whenthe magnetic coating is formed. More preferably, it should be 20 to 40μm. The magnetic core member which is formed by a magnetic coating whichis formed on a surface of the insulating resin film or sheet is formedby applying and drying a paint which contains a powder or a flake whichis formed by a magnetic member on a surface of the insulating resin filmor sheet. Also, it is possible to obtain the first magnetic core member113 having 0.8 mm thickness or thinner which has been difficult to formin an injection molding operation. Thus, it is possible to obtain athinner antenna coil.

Next, a third embodiment of the present invention is shown in FIGS. 6and 7. Hereinafter, the same reference numerals are applied tocorresponding members as shown in the above embodiment so as to omit therepeated explanation thereof.

In the present embodiment, a second magnetic core member 114 covers theforwarding section 112 a so as not to overlap the returning section 112b on the surface of the insulating member 111 such that its end sectionoverlaps the end section of the neighboring first magnetic core member113. The second magnetic core member 114 in the present embodiment isformed by a magnetic coating which is formed by applying and drying apaint which contains a powder or a flake which is made of a magneticmember. That is, the paint which contains a powder or a flake which isformed by a magnetic member is applied on a surface of the electricallyinsulating member 111 so as to cover the forwarding sections 112 awithout covering the returning sections 112 b; thus, a magnetic coatingwhich forms the second magnetic core member 114 is formed by dryingafterwards.

Here, for a powder for a magnetic member which is contained in a paint,an atomized powder can be used such as a carbonyl iron powder, aniron-Permalloy powder, and a reduced iron powder. On the other hand, fora flake which is formed by crushing the above powder by a ball end milletc. and flattening the powder mechanically can be used. Also, a flakewhich is formed by colliding a melt alloy grain of an iron or cobaltamorphous alloy onto a surface of a copper which is cooled by a watercan be used. Also, the thickness of the formed magnetic coating ispreferably 10 to 800 μm. More preferably, it should be 30 to 300 μm.Here, if it is not possible to obtain a predetermined thickness in asingle applying operation for a paint, it is possible to obtain adesirable thickness of coating by applying and drying the same paintrepeatedly. It is possible to obtain a relatively thin magnetic coremember 114 which is formed by a magnetic coating by a simple operationin which a paint is applied and dried.

In the antenna coil which is formed in this way, the magnetic coremember 114 is formed by a magnetic coating; therefore, it is possible toobtain the magnetic core member 114 having 0.8 mm or thinner thicknesswhich is difficult to form in the injection molding operation.Therefore, the thickness can be thin. Also, the magnetic core member 114is bonded on a surface of the insulating member 111 so as to cover theforwarding sections 112 a and overlap the end sections of the firstmagnetic core member 113 which neighbors the end sections. Therefore,the magnetic flux which passes through the first magnetic core member113 moves to the magnetic core member 114 in the end sections of thefirst magnetic core member 113 so as to pass above the forwardingsections 112 a as shown by a true-line arrow in FIG. 6. The magneticflux moves to the end sections in the neighboring first magnetic coremember 113 from the end section s of the magnetic core member 114.Therefore, the magnetic core member 114 introduces the magnetic fluxwhich passes through the first magnetic core member 113 to a surface ofthe insulating member 111 in the forwarding sections 112 a. The magneticflux passes through the first magnetic core member 113 and the magneticcore member 114 while moving the first magnetic core member 113 and themagnetic core member 114. Therefore, the forwarding sections 112 a andthe returning sections 112 b exist on a top surface and a back surfaceof the magnetic flux alternatively. Therefore, the continuous conductivemember 112 which includes the forwarding sections 112 a and thereturning sections 112 b is unified with the antenna coil which is woundaround the magnetic flux. Therefore, it is possible to obtain an antennacoil 10 relatively easily which has the same characteristics as thecharacteristics of the conventional antenna coil in which a firstconductive member is produced by winding a lead wire around an outersurface of the magnetic core member. Therefore, it is possible toimprove the productivity in mass production with compared to a case of aconventional antenna coil in which a copper wire is wound.

Next, a fourth embodiment of the present invention as shown in FIGS. 8and 9. Hereinafter, the same reference numerals are applied tocorresponding members as shown in the above embodiment so as to omit therepeated explanation thereof.

In the present embodiment, the continuous conductive member 112 has twolead wires 21, 22. The lead wires 21, 22 are formed so as to wind on asurface of the insulating member 111 with predetermine intervals alongwith each other respectively. Forwarding sections 21 a, 22 a andreturning sections 21 b, 22 b are formed alternatively in two lead wires21, 22. The forwarding sections 21 a, 22 a and the returning sections 21b, 22 b are connected alternatively by a plurality of connectingsections 21 c, 22 c. Lead sections 21 d, 22 d are formed on both ends ofthe two lead wires 21, 22 respectively. The continuous conductive member112 is formed by connecting the lead section 21 d in the end section ofa lead wire 21 to a lead section 22 d in a starting end section of theother neighboring insulating member 111.

Consequently, the first magnetic core member 113 is bonded on a backsurface of the electrically insulating member 111 so as to cover thereturning sections 21 b, 22 b from a back surface of the electricallyinsulating member 111 without overlapping the forwarding sections 21 a,22 a. The second magnetic core member 114 is bonded on a surface of theelectrically insulating member 111 so as to cover the forwardingsections 21 a, 22 a and overlap the end sections of the first magneticcore member 113 to which the end sections of the second magnetic coremember 114 neighbors without overlapping the returning sections 21 b, 22b.

In the antenna coil 10 which is formed in this way, the conductivemember 112 is formed by two lead wires 21, 22. Therefore, the quantityof the forwarding sections 21 a, 22 a and returning sections 21 b, 22 bwhich exist on a top surface and a back surface of the magnetic fluxalternatively which passes through the first magnetic core member 113and the second magnetic core member 114 increases with compared to acase in which a conductive member is formed by a single conductive wire.Therefore, the turning number increases. Thus, it is possible to improvethe characteristics of the antenna coil by increasing the turningnumber.

Here, in the above third embodiment as explained above, explanations aremade for a case in which the conductive member 112 is formed by the twolead wires 21, 22. As shown in FIG. 10, it is acceptable if theconductive member 112 is formed by three lead wires 31, 32, 33. Also, itis acceptable if the conductive member 112 is formed by several piecessuch as 4, 5, 6, 7, or 9 pieces of lead wires which are not shown in thedrawing. If the turning number is increased, a so called turning numberincreases; therefore, it is possible to improve the characteristics ofthe antenna coil by increasing the turning number.

Also, in the above embodiments, explanations are made for the firstmagnetic core member 113 which is made by injecting a composite memberinto a mold and the second magnetic core member 114 which is made by amagnetic coating. It is acceptable if the first magnetic core member ismade by a magnetic coating. It is acceptable if the second magnetic coremember is made by a soft magnetic metal member, a powder of a flakewhich is made by an amorphous or a ferrite and a plastic compositemember, a plate or a film which is made of a soft magnetic metal member,an amorphous film or its layered member, or a ferrite.

Next, an example of the present invention is explained in detailtogether with comparative examples.

EXAMPLE 3

As shown in FIGS. 4 and 5, a conductive member 112 is formed on asurface of the electrically insulating member 111 which is formed by anelectrically insulating film. For the electrically insulating film, apolyimide film is used which has a dimension such as 50 μm thickness,and longitude and a latitude such as 65 mm×55 mm. A copper film having35 μm is layered and bonded on a main surface of the polyimide film. Acontinuous conductive member 112 a is formed on a surface of thepolyimide film by etching the copper film such that the conductivemember 112 has three winding forwarding sections 112 a and three windingreturning sections 112 b both of which has 40 mm length are formed on asurface of the polyimide film alternatively with an interval of 10 mm.The conductive member 112 has 0.8 mm width.

After that, the first magnetic core member 113 having a dimension suchas 1 mm thickness and longitude and a latitude such as 40 mm×20 mm isbonded on a back surface of the conductive member 112 on which theconductive member 112 is disposed. For the first magnetic core member113, a member is used which is formed by injecting the composite membercontaining 92 weight % of a carbonyl iron powder and a nylon resin intoa mold. The first magnetic core member 113 is bonded such that the firstmagnetic core member 113 should cover the returning sections 112 b froma back surface of the electrically insulating member 111 withoutoverlapping the forwarding sections 112 a.

Consequently, the conductive member 116 which is formed by an aluminumplate having a dimension such as 0.1 mm thickness and longitude and alatitude such as 70 mm×60 mm is bonded on a back surface of theelectrically insulating member 111 so as to cover the first magneticcore member 113. Thus, an example 1 is an antenna coil which has onlythe first magnetic core member 113 in this way.

EXAMPLE 4

An antenna coil which has only the same first magnetic core member 113as that in the example 3 is obtained. The second magnetic core member114 which as the same shape and size as the first magnetic core memberof the example 1 is prepared by a composite member which is the same asthat in the example 1. Consequently, an antenna coil shown in FIGS. 6and 7 is obtained by bonding the second magnetic core member 114 on asurface of the electrically insulating member 111 so as to cover theforwarding sections 112 a and overlap the end sections of the firstmagnetic core member 113 which neighbors the end sections withoutoverlapping the returning sections 112 b. In this way, an example 4 isan antenna coil which has both the first magnetic core member 113 andthe second magnetic core member-114.

COMPARATIVE EXAMPLE 2

A coil main body 2 is formed on an electrically insulating film as asingle base plate 1 as shown in FIG. 24. For an electrically insulatingfilm 1, a polyimide film is used which has a dimension such as 50 μmthickness, and longitude and a latitude such as 50 mm. A copper filmhaving 35 μm thickness is layered and bonded on a surface of thepolyimide film 1. By etching the copper film, a conductive member isformed. Thus, a coil main body 2 is formed by winding the conductivemember helically four times around a main surface of the polyimide film.The conductive member is formed so as to have 0.8 mm thickness. An outershape of the coil main body 2 which is formed by the conductive memberis 45 mm×45 mm. The central section which is surrounded by the coil mainbody 2 is formed so as to be square of 37 mm×37 mm. Consequently, aconductive member which is not shown in drawing is formed by an aluminumplate having a dimension such as 0.1 mm thickness and longitude and alatitude such as 70 mm×60 mm so as to be bonded on a back surface of thebase plate 1 which is made of an electrically insulating film. Anexample 2 is an antenna coil in which a helical coil main body 2 isformed around the base plate 1 which is made of an electricallyinsulating film.

COMPARATIVE EXAMPLE

For an article, an acrylic plate having a dimension such as 0.116 mmthickness and 100 mm×100 mm, and an aluminum plate having the same shapeand size as the acrylic plate, and a soft steel plate are preparedrespectively. Antenna coils according to the above example 1, 2 and acomparative example 1 are disposed on surfaces of the acrylic-plate, analuminum plate, and a soft steel plate respectively. The antenna coilsare disposed such that their conductive member should contact thearticles directly. Consequently, measurement terminals in a measurementdevice (Model 4395 commercially available under trade mark which isregistered by HEWLETT PACKARD) for measuring characteristics in a coilare connected to both ends of the conductive member 12 of these antennacoils. Thus, L value and Q value are measured respectively by themeasurement device.

Also, condensers 116 are connected to the antenna coils in thecomparative example 2 and the example 3 so as to obtain an EAS tag whichis operable at 8.2 MHz. It is confirmed whether or not the tags areoperated if the tags are disposed on surfaces of the acrylic plate, thealuminum plate, and the soft steel plate respectively. The result isshown in a TABLE 2 respectively.

TABLE 2 Acrylic Aluminum Soft Steel Article Plate Plate Plate Example 3L(μH) 2.186 2.142 2.23 Q 80.7 79.5 78.2 Confirmation Operated OperatedOperated of Operation Example 4 L(μH) 2.662 2.635 2.71 Q 76.5 74.8 73.5Confirmation Operated Operated Operated of Operation Comparative L(μH)2.218 1.025 2.345 Example 2 Q 100.3 50.8 12.1 Confirmation Operated NotNot of Operation Operated Operated

As understood clearly from the TABLE 2, the L values do notsubstantially vary on the acrylic plate, the aluminum plate, and thesoft steel plate in the examples 3 and 4. The Q values decreases notgreatly on the aluminum plate and the soft steel plate with compared toa case of the acrylic plate. However, in the example 2, the L valuevaries on the aluminum plate with compared to the acrylic plate. Also,the Q value decreases greatly in a case of the soft steel plate. It isestimated that this is caused because the direction of the magnetic fluxis orthogonal to a surface on the plate in the examples such that themost of the part of the magnetic flux reaches to the plate even if theconductive member is bonded in contrast to cases of the examples 3 and 4in which the direction of the magnetic flux which is generated from thecoil is parallel with a surface of the plate. Also, the tag in which theIC chip is connected to the antenna coils of the example 3 and theexample 4 is operable on any surfaces of the acrylic plate, the aluminumplate, and the soft steel plate. In contrast, the tag in which the ICchip is connected to the antenna coil of the comparative example 2 isoperable only when it is disposed on a surface of the acrylic plate. Thetag in which the IC chip is connected to the antenna coil of thecomparative example 2 is not operated when it is disposed on a surfaceof the aluminum plate and the soft steel plate. It is estimated thatthis is because the L value varies on the aluminum plate; thus, theresonation frequency varies and the energy is absorbed by a steel plate;thus, a loss is generated.

Next, a fifth embodiment of the present invention is explained based onthe drawings.

As shown in FIGS. 11 and 12, the tag antenna coil 10 of the presentinvention comprises a coil main body 211 a which is made by a conductivemember 211 which is wound helically in a plate or plane and a sheetmagnetic core member 213 which is bonded on a surface of the coil mainbody 211 a. The coil main body 211 a in the present embodiment is formedby winding the conductive member 211 helically around a main surface ofthe electrically insulating film or the sheet 212. A film or a sheet 212such as a polyethylene terephthalate or a polyimide is used for theelectrically insulating film or a sheet 212. The conductive member 211can be formed if a conductive film which is bonded on a main surface ofthe electrically insulating film or the sheet 212 is etched or punchedin a predetermined pattern. Also, the conductive member 211 can beformed if a conductive film which is bonded on a main surface of theelectrically insulating film or the sheet 212 is printed by ascreen-printing method or a vapor deposition method.

Processes for forming the conductive member 211 on the film 212 by theetching operation is explained. First, a member which is formed byattaching a copper film onto an entire main surface of the film 212 isprepared. An anti-etching paint is printed onto the copper film by asilk-screen method. The anti-etching paint is printed onto the copperfilm helically from a center in a rectangular manner or circular mannerbecause it is necessary to form the coil main body 211 a by theconductive coil member 211. After that, the copper film on which theanti-etching paint is not applied is removed in the etching operationafter drying the anti-etching paint. The copper film area on which ananti-etching paint is applied remains on a main surface of the film.After that, by removing the anti-etching paint from the copper film, theconductive member 211 which is formed by the copper film which remainson a main surface of the film 212 is formed. Here, the anti-etchingpaint on a main surface of the film 212 in FIGS. 11 and 12 is appliedhelically and circularly from the center; therefore, the conductivemember 211 which is formed on a main surface of the film 212 has a coilmain body 211 a which is formed helically from the center in a circularmanner. By the etching operation, it is possible to form the conductivemember 211 on a main surface of the electrically insulating film 212 orthe electrically insulating sheet relatively easily and in low cost.

On the other hand, it is possible to form the magnetic core member 213by a plate or sheet soft magnetic metal member, or a soft magnetic metalmember, a powder or a flake which is formed by an amorphous or ferrite,or composite member of plastic. Also, it is acceptable if the magneticcore member 213 is formed by an amorphous film or its layered membersuch as an Fe amorphous alloy (METGLAS 2605-2 commercially availableunder a trademark of Alliedchemical corp.) and a Co amorphous alloy(METGLAS 2712A commercially available under a trademark ofAlliedchemical corp.) or a ferrite which is formed in a square manner.

Explanations for the plastic which is used for the composite member isomitted because it is the same as that in the first embodiment.

A sheet member which is formed by injecting the composite member into anoval circular manner into a mold is used for the magnetic core member213 in FIGS. 11 and 12. This magnetic core member 213 is bonded onanother main surface of the electrically insulating film 212. Themagnetic core member 213 is bonded on another main surface of theelectrically insulating film 212 by applying a bond on either one orboth of the magnetic core member 213 and the electrically insulatingfilm 212, and after that, layering the magnetic core member 213 onanother main surface of the electrically insulating film 212. Such alayering operation and bonding operation are performed such that themagnetic core member 213 crosses a part of the coil main body 211 a insuch a way that an end 213 a of the magnetic core member 213 ispositioned in a central section 211 b which is surrounded by the coilmain body 211 a and an other end 213 b of the magnetic core member 213is positioned outside of the coil main body 211 a.

As shown in FIG. 11, in the antenna coil 1 in the present embodiment, aconductive member 216 in a sheet or a plate manner is bonded on asurface of the coil main body 211 a. Specifically, the conductive member216 is bonded on another main surface of the electrically insulatingfilm or the sheet 212 so as to cover the magnetic core member 213 whichis bonded on another main surface of the electrically insulating film ora sheet 212. The conductive member 216 is formed by a conductivematerial such as a copper, or an aluminum. In a case in which themagnetic core member 213 has a conductivity, it is layered and bonded soas to have an insulating film therebetween. It is preferable that thethickness of the conductive-member 216 is 0.01 mm to 5 mm. By formingthe conductive member 216 with a thickness 0.01 mm to 5 mm, an intervalbetween the conductive member 216 and the conductive member 211 increases. Thus, it is possible to improve the Q value of the coil mainbody 211 a which is formed by the conductive member 211; therefore, itis possible to improve the performance of the antenna coil 10. Also, itis preferable that an electric resistance of the conductive member 216in 1 cm width and 1 cm length is 5Ω or less.

In such an antenna coil 10 which is formed in this way, it is possibleto form its thickness very thin. Also, because of such a thin thickness,the antenna 10 does not actually protrude from the article 18 even ifthe antenna coil 10 is attached to the article 18. Also, the magneticcore member 213 is layered on a surface of the coil main body 211 awhile crossing a part of the coil main body 211 a; therefore, themagnetic flux which is generated by an electric current which passes tothe coil main body 211 a which is formed by the conductive coil member211 passes through the magnetic core member 213. The magnetic flux whichpasses through the magnetic core member 213 describes a loop which isshown by a true-line arrow in FIG. 11. Because of this, even if the tagantenna coil 10 is attached to a surface of the article 18, its magneticflux direction is parallel with a surface of the article 18 as indicatedby an arrow in FIG. 11. Even if the article 18 is formed by a metalmember, an eddy current which is generated in the article 18 isrestricted; thus, the resonation frequency in the antenna coil 10 is notaffected by the metal article. Thus, the antenna coil 10 is operatedreliably.

In particular, in the present embodiment, the coil main body 211 a isformed by etching the conductive film which is bonded on an entire mainsurface of the electrically insulating film 212 in a predeterminedpattern; therefore, it is possible to obtain the RFID tag or an EAS tagrelatively easily only by connecting the electrically insulating film212 on which the IC chip or a resonation condenser which are not shownin the drawing is mounted to the coil main body 211 a. Also, in the RFIDtag in which the IC chip is connected to the antenna coil 10, theantenna coil 10 is attached to the article 18 such that the conductivemember 216 should be disposed between the article 18 and the coil mainbody 211 a. By doing this, the magnetic flux which is generated by anelectric current which passes in the coil main body 211 a passes mainlyin the magnetic core member 213; thus, the magnetic flux does not passin the article 18. Furthermore, in the present embodiment, theconductive member 216 is layered and boned on another main surface ofthe electrically insulating film or a sheet 212 so as to cover themagnetic core member 213; thus, the conductive member 216 blocks theradio wave which is directed to the article. Therefore, with no regardto whether or not the article 18 is formed by a metal member, theantenna coil 10 receives its fewer influence. Even if a surface of thearticle is made from a metal member, the loss due to the eddy currentwhich is generated on the metal surface is not generated; thus, the RFIDtag is operated reliably even if it is attached to a section which isformed by a metal member of the article 18.

Also, in the antenna coil 10, the coil main body 211 a is formed by acontinuous conductive member 211 on a main surface of the electricallyinsulating film or the sheet 212. Therefore, its usage is easy; thus, itis possible to obtain the antenna coil 10 only in a simple operationsuch as a layering and bonding operation of the magnetic core member 213on another main surface of the electrically insulating film or the sheet212. Therefore, it is possible to improve the productivity in massproduction with compared to a case of a convention al antenna coil ofwhich conductive member has been produced by winding a lead wire aroundan outer surface of the magnetic core member.

Here, in the above embodiment, explanations are made for the magneticcore member 213 which is formed by a soft magnetic metal member, acomposite member, a plate or a film of a soft magnetic metal member, anamorphous film or its layered member, or a ferrite. It is acceptable ifthe magnetic core member 213 may be provided with an insulating resinfilm or a sheet and a magnetic coating which is formed on a surface ofthe insulating resin film or a sheet which are not shown in the drawing.Here, the thickness of the insulating resin film or sheet for formingthe magnetic coating is preferably 10 to 100 μm. More preferably, itshould be 20 to 40 μm. The magnetic core member which is formed by theinsulating resin film or a sheet and a magnetic coating which is formedon a surface thereof is made b applying and drying a powder which ismade of a magnetic member or a paint which includes a flake on a surfaceof the insulating resin film or the sheet. By doing this, it is possibleto obtain the magnetic core member 213 having 0.8 mm thickness which hasbeen difficult to produce in an injection molding operation; thus, it ispossible to obtain further thinner antenna coil 10.

Next, a sixth embodiment of the present invention is shown withreference to FIGS. 13 and 14. Hereinafter, the same reference numeralsare applied to corresponding members as shown in the above embodiment soas to omit the repeated explanation thereof.

In the present embodiment, the coil main body 211 a which is wound in arectangular helical manner is formed on a main surface of theelectrically insulating film 212 by the conductive member 11. In thepresent embodiment, the conductive coil member 211 is formed byperforming the screen printing operation or a vapor deposition operationof the conductive member such as Cu, Al, Zn on a main surface of theelectrically insulating film 212 in a rectangular helical manner. Byforming the conductive coil member 211 on a main surface of theelectrically insulating film 212 by performing the printing operation orthe vapor deposition operation, it is possible to perform relativelylarge production by a relatively cheap cost.

A powder which is made of a magnetic member of a paint which includes aflake is applied on another main surface of the electrically insulatingfilm 212 so as to cross a part of the coil main body 211 a. The paint isapplied such that an end 213 a is positioned in a central section 211 bwhich is surrounded by the coil main body 211 a and another end 213 b ispositioned outside of the coil main body 211 a. After that, byperforming a drying operation, a magnetic coating which forms themagnetic core member 213 is formed. The magnetic core member 213 whichis made of a magnetic coating which is formed in this way is layered onanother main surface of the film or the sheet 212.

Here, for the powder which is included in the paint, an atomized powdersuch as a carbonyl iron powder and an iron-Permalloy, and a reduced ironpowder etc. On the other hand, for a flake of the magnetic member, aflake which is formed by molding a powder which is crushed by a ball-endmill etc. and flattening the powder mechanically and a flake which isformed by colliding a melt grain of iron or a cobalt amorphous alloy toa water-cooled copper are used. Also, the thickness of the formedmagnetic coating should be 10 to 800 μm. More preferably, it should be30 to 300 μm. Here, if it is not possible to obtain a predeterminedthickness in a single applying operation for a paint, it is possible toobtain a desirable thickness of coating by applying and drying the samepaint repeatedly. The magnetic coating serves for the magnetic coremember 213. It is possible to obtain the tag antenna coil 10 which hasthe magnetic core member 213 which is formed by a magnetic coating in asimple operation such as only applying and drying the paint.

The antenna coil which is formed in this way has the magnetic coremember 213 which is made of a magnetic coating. Therefore, it ispossible to obtain the magnetic core member 213 having 0.8 mm thicknessor thinner which has been difficult to form in the injection moldingoperation. Thus, it is possible to obtain thinner thickness. Therefore,it is possible to obtain the antenna coil 10 of which magnetic fluxdirection is parallel with the surface of the article such that theantenna coil does not actually protrude from the article. Also, themagnetic core member 213 is formed a magnetic coating which is formed onthe electrically insulating film 212 or a sheet; therefore, it ispossible to omit a step for bonding the magnetic core member 213 in theabove explained embodiment; thus, it is possible to obtain the antennacoil 10 in further simple operation. Also, it is possible to improve theproductivity in the mass production for the antenna coil 10.Furthermore, the magnetic coating is formed by applying and drying thepaint; thus, if a flake which is formed y the magnetic member isincluded in the paint, and if the flake is disposed in parallel with asurface of the electrically insulating film 212 or the sheet, it ispossible to improve the characteristics of the magnetic core member 213.

Here, in the above explained embodiment, the coil main body is formed bywinding a conductive member helically around a main surface of theelectrically insulating film 212. However, it is not necessary to formthe coil main body on the electrically insulating film as long as it ispossible to maintain the conductive member so as to be wound helicallyin a plane. Specifically, it is acceptable if the coil main body isformed by a conductive member which is wound helically in a plane bywinding a lead wire of which surface is coated by an insulating layerhelically in a plane or by punching the conductive plate member such asan aluminum sheet or a copper plate.

Next, an example of the present invention is explained in detail withreference to a comparative example.

COMPARATIVE EXAMPLE 3

An air-core coil in which a coil main body is formed by a conductivemember on a main surface of an electrically insulating film is obtained.For an electrically insulating film, a polyimide film having 50 μm andlongitude and latitude such as 50 mm×60 mm is used. A copper film having35 μm thickness is layered and bonded on a main surface of the polyimidefilm. A coil main body which is wound helically four times rectangularlyis formed on a main surface of the polyimide film by a continuousconductive member by etching the copper film. The conductive member isformed to be 0.8 mm width. An outer shape of the coil main body which isformed by the conductive member is 18 mm×47 mm. A comparative example 1is an antenna coil which is formed only by a conductive member which isdisposed on the electrically insulating film.

EXAMPLE 5

An air-core coil is formed on an electrically insulating film which isthe same as the electrically insulating film of the comparative example3 by the same conductive member as that of the comparative example 1 bythe process which is the same as the process in the comparativeexample 1. Also, an ink which contains a magnetic flake is preparedseparately. The ink is applied and dried on another main surface of theelectrically insulating film. The magnetic core member is formed onanother main surface of the electrically insulating film which forms asurface of the coil main body such that, an end of the magnetic coremember is positioned in a central section which is surrounded by thecoil main body so as to cross a part of the coil main body, and anotherend of the coil main body is positioned outside of the coil main body. Acomparative example 5 is an antenna coil which has a magnetic coremember which is made of a magnetic coating on a surface of the coil mainbody in this way.

EXAMPLE 6

An air-core coil is formed on an electrically insulating film which isthe same as the electrically insulating film of the comparative example3 by the same conductive member as that of the comparative example 3 bythe process which is the same as the process in the comparative example3. Also, a magnetic core member is prepared which is made of a layeredmember of an amorphous films which are made by layering four pieces ofamorphous films having 10 mm×60 mm of outer shape and 20 μm thicknessseparately. The magnetic core member is bonded on another main surfaceof the electrically insulating film; thus, an antenna coil which has amagnetic core member on a surface of the coil main body. The magneticcore member is bonded such that an end of the magnetic core member ispositioned in a central section which is surrounded by the coil mainbody so as to cross a part of the coil main body, and another end of thecoil main body is positioned outside of the coil main body. In this way,an example 6 is an antenna coil which has a magnetic core member whichis formed by a layered member of the amorphous film on a surface of thecoil main body.

EXAMPLE 7

An air-core coil is formed on an electrically insulating film which isthe same as the electrically insulating film of the comparative example3 by the same conductive member as that of the comparative example 3 bythe process which is the same as the process in the comparative example3. Also, a magnetic core member is prepared which is made of a compositemember having 35 mm×52 mm of outer shape and 0.87 mm thicknessseparately. The composite member is made of a grain iron powder and aplastic as a soft magnetic metal member. The magnetic core member whichis made of the composite member is bonded on another main surface of theelectrically insulating film; thus, an antenna coil which has a magneticcore member on a main surface of the coil main body is obtained. Themagnetic core member is bonded such that an end of the magnetic coremember is positioned in a central section which is surrounded by thecoil main body so as to cross a part of the coil main body, and anotherend of the coil main body is positioned outside of the coil main body.In this way, an example 7 is an antenna coil which has a magnetic coremember which is formed by a composite member on a surface of the coilmain body.

COMPARATIVE EXAMPLE

Measurement terminals in a measurement device (Model 4395 commerciallyavailable under trade mark which is registered by HEWLETT PACKARD) formeasuring characteristics in a coil are connected to both ends of theconductive member (X and Y in FIG. 14) which forms the coil main body ofthe antenna coil according to the comparative example 3 and the examples5 to 7. Thus, L value and Q value of the coil main boy in apredetermined frequency are measured respectively by the measurementdevice.

Also, for an article, an aluminum plate is prepared which has adimension such as 100 mm×100 mm and thickness of 0.16 mm. IC chips areconnected to both end sections (X and Y shown in FIG. 14) in theconductive member which forms the coil main bodies according to thecomparative example 3 and the examples 5 to 7. A tag is formed by the ICchips and the antenna coil so as to be operable in 213.56 MHz. It isconfirmed whether or not the tags are operated if the tags are disposedon surfaces of the aluminum plate respectively. The result is shown in aTABLE 3.

TABLE 3 Comparative Example 5 Example 6 Example 7 Example 3 MagneticCore Member No Magnetic Magnetic Composite Core Predetermined CoatingAmorphous Member Member Frequency L L L L (MHz) (μH) Q (μH) Q (μH) Q(μH) Q 1 1.315 7.8 1.395 7.6 1.372 8.1 0.680 2.0 2 1.296 13.6 1.357 11.61.351 14.5 0.667 3.3 3 1.287 18.9 1.343 14.4 1.344 19.7 0.662 4.4 41.285 23.3 1.335 16.0 1.340 24.2 0.660 5.2 5 1.286 27.4 1.331 17.3 1.34028.6 0.659 6.0 6 1.286 31.3 1.328 18.1 1.340 32.6 0.659 6.6 7 1.287 34.51.326 18.9 1.341 36.2 0.659 7.2 8 1.290 37.3 1.325 18.6 1.343 39.1 0.6607.5 9 1.292 40.6 1.325 19.2 1.346 42.7 0.660 8.0 10 1.295 43.0 1.32519.3 1.348 45.1 0.661 8.4 11 1.299 45.2 1.326 19.4 1.352 47.9 0.663 8.712 1.305 47.0 1.330 19.4 1.358 50.6 0.665 9.0 13 1.313 48.4 1.333 19.41.363 52.3 0.668 9.2 14 1.316 50.3 1.336 19.4 1.390 55.3 0.673 9.5 151.322 51.3 1.403 19.3 1.376 57.1 0.683 9.6 20 1.361 53.7 1.369 18.81.415 64.7 0.691 10.1 Operation Operated Operated Operated Not Operated

As clearly understood from the TABLE 3, the Q value is improved in theexamples 5 to 7 with compared to the comparative example 3. It isestimated that this is caused by an existence of the magnetic coremember. Also, the tags in which the IC chips are connected to theantenna coils of the examples 5 to 7 are operable even if the tags aredisposed on the surface of the aluminum plate. In contrast, the tag inwhich the IC chips are connected to the antenna coil of the comparativeexample 3 is not operable. It is estimated that this is because themagnetic flux which is generated from the coil is parallel with asurface of the plate in the antenna coil of the examples 5 to 7; thus,the eddy current is restricted from being generated when the magneticflux reaches to a surface of the aluminum plate. On the other hand, inthe comparative example 3, the direction of the magnetic flux isorthogonal to a surface of the plate; thus, a most part of the magneticflux reaches to the aluminum plate; therefore, the L value of theantenna coil varies and the resonation frequency varies, and the energyis absorbed in the iron plate so as to be a loss there.

Next, a seventh example of the present invention is explained withreference to drawings.

As shown in FIGS. 15 and 16, an RFID tag 12 as a transponder is attachedon a surface of an article 311. The tag 12 comprises an IC chip 313 inwhich a different identical information per an article 313 is stored anda transponder antenna 314 which is connected to the IC chip 313electrically. In the present embodiment, a most part of the IC chip 313to which the transponder is attached is formed by a metal member. Theantenna 314 of the present invention comprises a conductive member 314 aof which back surface is attached to the article 11 so as to be in aplate manner by the conductive member and a coil main body 314 b whichis wound helically around a surface of the conductive member 314 a viaan insulating member 316.

For the conductive member 314 a, it is possible to name a sheet, plate,or a film which are made of a conductive member such as a copper or analuminum. A conductive member both ends of which are connected isacceptable. As shown in FIG. 16 in an enlarged manner, it is preferablethat the insulating member 316 should be a non-conductive sheet, plate,or film such as a polyethylene, or a polyethylene terephthalate. Also,it is acceptable that the conductive member 314 a may be a conductivecoating which is formed by applying and drying a conductive ink on aback surface of the insulating member 316 as long as the conductivemember 314 a has a conductivity. It is preferable that the conductivecoating is a member which contains a grain or a flake which are made ofa silver or graphite. Furthermore, it is acceptable if the conductivemember 314 a may be a conductive plating layer or a vapor depositionlayer which are layered on a back surface of the insulating member 316.In a case in which a conductive member 314 a which is made of a paint, aplating layer, or a vapor deposition layer is used, it is preferablethat a thickness of the insulating member 316 is 0.01 to 5 mm. Byforming the insulating member 316 with a thickness of 0.01 to 5 mm, aninterval between the conductive member 314 a and the coil main body 314b increases; thus, it is possible to improve the performance of theantenna by improving the Q value in the coil main body 314 b. Also, anelectric resistance of the conductive member 314 a per 1 cm width and 1cm length should be is 5◯ or less.

For the helical coil main body 314 b, a member which has been usedconventionally is used. That is, for the coil main body 314 b, it ispreferable that it is made by winding the coated lead wire.Alternatively, it is possible to name a method in which an unecessarypart is removed from a conductive layer such as an aluminum film or acopper film according to an etching method or a punching method whichare layered on an insulating plastic sheet which is a insulating member316 so as to form a helical manner. If the conductive member 314 a isformed by a coating, a plating layer, or a vapor deposition layer whichare formed on a back surface of the insulating member 316, it isacceptable that a film such as an aluminum film is layered on a surfaceof the insulating member 316 directly, an unnecessary part of thealuminum film or the copper film is removed according to an etchingmethod, a helical coil main body 314 b is formed on its surfacedirectly. The coil main body 314 b is formed such that the turningnumber and the turning diameter are adjusted such that a predeterminedcharacteristic value can be obtained under condition that the coil mainbody 314 b is wound around a surface of the conductive member 314 a.Here, in the present embodiment, it is understood that an IC chip 313 isbonded on the conductive member 314 a directly under condition that itis connected to both ends of the coil main body 314 b.

In the transponder antenna 314 which is formed in this way, itscharacteristics value varies usually if the coil main body 14 is fixedon the conductive member 314 a. The coil main body 314 b is adjusted soas to obtain a predetermined characteristic value under condition thatthe coil main body 314 b is wound around a surface of the conductivemember 314 a. Therefore, by transmitting a radio wave which has apredetermined frequency from a transmitting/receiving antenna in aninterrogator which is not shown in the drawing to the antenna 314, it ispossible to activate the tag 12 reliably. Also, in the antenna 314, thecoil main body 314 b which actually receives the radio wave which has apredetermined frequency is wound around a surface of the conductivemember 314 a in advance; thus, a predetermined characteristics value isobtained. Therefore, even if the antenna 314 is attached to an articlewhich is made of a metal member, it never occurs that thecharacteristics value of the coil main body 314 b varies greatly.Therefore, a space which has been necessary for attaching theconventional antenna 314 onto a metal article is not necessary.Therefore, it is possible to avoid that the tag 12 protrudes from thearticle to a great extent and activate the tag 12 reliably without beingaffected undesirably from the metal article.

Here, if the Q value of the coil main body 314 b decreases greatly, asshown in FIGS. 17 and 18, it is preferable to form a hole 314 c in asection which is surrounded by the coil main body 314 b in theconductive member 314 a. In a case in which a hole 314 c is formed inthe conductive member 314 a in a central section of the coil main body314 b, even if an eddy current is generated in the conductive member 14a by a radio wave which penetrates through the coil main body 314 b, theeddy current is generated in a narrow area near the coil main body 314 bdue to an existence of the hole 314 c; thus, it is possible to restrictthe Q value from being reduced in the coil main body 314 b. As a result,it is possible to attach the transponder antenna 314 directly withoutvarying its characteristics even if a surface of an article is made fromany material.

FIG. 19 shows an eighth embodiment of the present invention. In FIG. 19,the same reference numeral indicates the same reference numeral shown inFIGS. 15 and 16.

The present embodiment is a transponder antenna 24 in which a softmagnetic member 26 which is formed in a plate manner is disposed betweenthe conductive member 314 a in the antenna in the above explained firstembodiment and the coil main body 314 b. Here, explanations for theconductive member 314 a and the coil main body 314 b are omitted becausethose are the same as those in the above first embodiment.

It is preferable that the soft magnetic member 26 is formed by eitherone of the soft magnetic member such as an amorphous alloy, a Permalloy,an electromagnetic steel, a silicon steel, a sendust alloy, a quenchsolidified member for Fe—Al alloy or a soft magnetic ferrite, a castedmember, a rolled strip member, a forged member, or a sintered member.Also, product of a transmission rate of the soft magnetic member 26 anda thickness represented in a unit such as mm indicates 0.5 or larger.Also, it is acceptable that the soft magnetic member 26 is a softmagnetic metal member, a composite which includes a powder or a flakewhich is formed by a soft magnetic metal member or a soft magneticferrite, or a coating which includes a powder or a flake which is formedby a soft magnetic metal member or a soft magnetic ferrite as long asthe soft magnetic member 26 has a conductivity. Here, it is possible touse a thermo-plastic plastic member which has a desirable formability ora thermosetting plastic which has a desirable heat resistance for aplastic in a composite. Also, a powder for the soft magnetic metalmember includes an atomized powder such as a carbonyl iron powder and aniron-Permalloy, and a reduced iron powder etc. On the other hand, forsuch a flake for the soft magnetic metal member, it is acceptable if anamorphous alloy flake be used which is formed by crushing a softmagnetic metal powder which is obtained by an atomizing method by usinga crushing device or a ball-end mill and colliding a powder and a meltalloy grain which are mechanically flattened onto a surface of a copperwhich is cooled by a water.

Also, in a case in which a plurality of flakes which are made of a softmagnetic metal member or a soft magnetic ferrite are used, it isacceptable if the soft magnetic member 26 may be formed by a bondedsheet which is made by bonding the flakes on a surface of a base sheetwhich is made of a plastic closely. Also, it is acceptable if the softmagnetic member 26 is formed by disposing a plurality of flakes closelywhich are made of a soft magnetic metal member or a soft magneticferrite on a surface of a base sheet which is made of a plastic andcovering it by a cover sheet which is made of a plastic so as to form alayered sheet in which a base sheet and the cover sheet are bonded.

Furthermore, in a case in which a composite member is used for the softmagnetic member 26, it is possible to form the soft magnetic member 26by performing the injection molding operation or a compressing moldingoperation. Such a soft magnetic member 26 which is formed in this way isrigid with compared with a member which is formed by a fragile ferrite;thus, it is difficult to be broken. Also, a powder or a flake of thesoft magnetic metal member or a soft magnetic ferrite are dispersed in aplastic or a rubber, thus, the powder or a fake are insulated from eachother. Therefore, an entire soft magnetic member 26 does not have aconductivity such that an eddy current is not generated if a highfrequency radio wave is received.

On the other hand, in a case in which the soft magnetic member 26 isformed by a composite member, it is preferable that the thickness of thepowder or the flake should by 20 μm or thinner so as to avoid generatingthe eddy current in the powder or the flake in the soft magnetic metalmember or the soft magnetic ferrite. Also, for a plastic, it ispreferable to use a resin such as an acrylic member, a polyester, apolyvinyl chloride, a polyethylene, a polystyrene, and an epoxy. Here,the thickness of the soft magnetic member 26 is not limited particularlyas long as there is shown an electromagnetic blocking effect. From anoperable use point of view, it is preferable in a range of 5 μm to 500μm.

In the transponder antenna 24 which is formed in this way, the coil mainbody 314 b is blocked from the conductive member 314 aelectromagnetically by the soft magnetic member 26; thus, the Q value inthe coil main body 314 b is improved. Therefore, it is possible toadjust the turning number or the turning diameter of the coil main body314 b relatively easy so as to obtain a predetermined characteristicvalue. Also, it is possible to obtain a predetermined characteristicvalue reliably even if the transponder antenna 24 is attached to asurface of a metal article. As a result, a space which has beennecessary for attaching the transponder antenna 24 to the metal productis not necessary; thus, the tag 12 is prevented from being protrudedfrom an article which is an object to be controlled. Thus, it ispossible to activate the tag 12 reliably without receiving an influencefrom a metal article.

FIG. 20 shows a third embodiment of the present invention. The samereference numeral in FIG. 20 shows a member which has the same referenceas those in FIGS. 15 to 19.

A transponder antenna 34 in the present embodiment comprises a softmagnetic member 26 which is formed in a plate manner such that a backsurface of the soft magnetic member 26 is attached to an article and acoil main body 314 b in which the turning number and the turningdiameter are adjusted so as to be opened on a surface of the softmagnetic member 26 so as to be wound helically and fixed so as to obtaina predetermined characteristic value. The detail of the coil main body314 b is the same as that in the above first embodiment. The softmagnetic member 26 is the same as that in the above second embodiment.The transponder antenna which is formed in this way is effective for acase in which it is possible to obtain a predetermined characteristicvalue only by blocking the soft magnetic member 26 electromagnetically.

In the transponder antenna 34, a predetermined characteristic value canbe obtained reliably by an electromagnetic blocking operation of thesoft magnetic member 26 even if the antenna 34 is attached on a surfaceof a metal article. Thus, it is possible to activate the tag 12 reliablyby transmitting a predetermined frequency of radio wave from atransmitting/receiving antenna in an interrogator which is not shown inthe drawing to the antenna 34. Therefore, a space which has beennecessary for attaching the antenna 34 onto a metal productconventionally is not necessary. Thus, the tag 12 is prevented frombeing protruded from an article which is an object to be controlled.Thus, it is possible to activate the tag 12 reliably without receivingan influence from a metal article.

Here, in the above explained seventh embodiment to the ninth embodiment,the coil main body 314 b is formed in an approximate circular helicalshape. However, it is acceptable if the coil main body 314 b is formedin an approximate oval helical shape, or an approximate helical squareshape shown in FIG. 21, or other helical shape.

Also, in the above explained seventh embodiment to the ninth embodiment,an RFID tag is named for the transponder. However, it is acceptable ifthe transponder antenna of the present invention is used for an EAS tag,a reader/writer, or other transponder.

Next, examples of the present invention are explained in detail togetherwith comparative examples.

EXAMPLE 8

As shown in FIGS. 15 and 16, a coil main body which has 50 mm of outerdiameter and 49 mm of inner diameter is produced by winding a coatedcopper wire which has 0.2 mm of diameter for 4 to 5 times. On the otherhand, a soft steel plate which as a dimension of 100 mm×100 mm and 0.16mm thickness and a non-metal acrylic plate which has the same shape andthe same size as the soft steel plate for a purpose of comparison areprepared. Aluminum plates which have a dimension of 50 mm×50 mm and 0.2mm thickness as a conductive member are disposed on a surface of thesoft steel plate and on a surface of the acrylic plate respectively. TheL1 value and the Q1 value for the coil main body are measured undercondition that the coil main body is disposed on the aluminum platewhich is disposed on the soft steel plate directly or with apredetermined interval. After that, the L2 value and the Q2 value forthe coil main body are measured under condition that the coil main bodyis disposed on the acrylic plate which is disposed on the soft steelplate directly or with a predetermined interval. Consequently, L1/L2 iscalculated.

EXAMPLE 9

A soft magnetic member is disposed between the coil main body and analuminum plate in the example 8. For the soft magnetic member, acomposite member which is formed by 72 weight % of a carbonyl iron and apolyethylene is injected into a mold and further compressed having 60 mmof outer diameter and 0.34 mm thickness is used. A coil main body in theexample 8 is contacted on a surface of the soft magnetic member 26.Consequently, the L1 value and the Q1 value of the coil main body ismeasured under condition that a back surface of the soft magnetic member26 contacts directly or with a predetermined interval on a surface ofthe aluminum plate which is disposed on a soft steel plate in theembodiment 8. In addition, the L2 value and the Q2 value of the coilmain body is measured under condition that a back surface of the softmagnetic member 26 contacts directly or with a predetermined interval ona surface of the aluminum plate which is disposed on an acrylic plate inthe embodiment 8. Thus, L1/L2 is calculated.

EXAMPLE 10

The L1 value and the Q1 value of the coil main body is measured underthe same condition as the example 8 except that an aluminum plate whichhas 100 μm thickness is used instead of the aluminum plate of theexample 8. The L2 value and the Q2 value of the coil main body aremeasured; thus, L1/L2 is measured.

EXAMPLE 11

The L1 value and the Q1 value of the coil main body is measured underthe same condition as the example 9 except that an aluminum plate whichhas 10 μm thickness is used instead of the aluminum plate of the example8. The L2 value and the Q2 value of the coil main body are measured;thus, L1/L2 is measured.

COMPARATIVE EXAMPLE 4

The L1 value and the Q1 value of the coil main body is measured undercondition that a coil main body is disposed on a surface of a soft steelplate as an article in the example 8 directly or with a predeterminedinterval. Also, the L2 value and the Q2 value of the coil main body ismeasured under condition that a coil main body is disposed on a surfaceof an acrylic plate directly or with a predetermined interval. Thus,L1/L2 is calculated.

The result for them are shown in TABLE 4.

TABLE 4 Acrylic Soft Steel Plate Plate L2 L1 L1/ Article (μH) Q2 (μH) Q1L2 Example 8 Interval between 0 0.667 15.5 0.677 15.2 99 Aluminum plate0.607 1.163 25.1 1.204 31.7 97 and coil main 1.214 1.482 45.5 1.511 34.498 body 1.821 1.694 52.7 1.702 49.4 100 2.428 1.892 57.2 1.862 54.9 102Example 9 Interval between 0 1.804 40.0 1.775 38.5 102 Aluminum plate0.607 2.019 43.9 2.021 42.2 100 and soft magnetic 1.214 2.187 46.9 2.18244.6 100 member 1.821 2.238 47.8 2.330 47.0 100 2.428 Example Intervalbetween 0 0.541 8.5 0.567 8.8 95 10 Aluminum film 0.607 1.187 27.7 1.17227.5 101 and coil main 1.214 1.547 39.1 1.499 37.3 103 body 1.821 1.76345.3 1.749 45.0 101 2.428 1.905 48.5 1.879 47.8 101 Example Intervalbetween 0 1.855 33.1 1.969 22.0 94 11 Aluminum film 0.607 2.129 36.42.146 36.6 99 and soft magnetic 1.214 2.281 38.2 2.329 37.9 98 member1.821 2.456 39.2 2.507 39.1 98 2.428 2.586 39.3 2.549 39.5 101 Compar-Inverval between 0 2.968 77.2 1.213 6.8 245 ative Metal Plate etc. 0.6072.968 77.2 1.359 9.3 218 Example 4 and coil main 1.214 2.968 77.2 1.61214.5 184 body 1.821 2.968 77.2 1.801 19.3 165 2.428 2.968 77.2 1.96324.1 151

As clearly understood from the TABLE 4, the L1/L2 value is large in thecomparative example 4. If the coil main body is disposed on the metalarticle directly, a variance ratio is large. It is understood that it isnot possible to activate the transponder if it is used in thetransponder actually. Consequently, as an interval to the metal memberbecomes larger, the variance ratio decreases. A fact is disclosed thatit is not possible to activate the transponder in a conventional antennawhich comprises only the coil main body unless the antenna is attachedto a metal surface via a spacer which has a predetermined thickness.

On the other hand, in the Example 8 and Example 10 in which an aluminumplate or an aluminum film are disposed between a metal plate and thecoil main body, it is understood that the L1/L2 which indicates avariance of the L decreases greatly. Therefore, it is understood thatthe present invention can be realized because even if a transponderantenna to which a coil main body is fixed of which turning number andthe turning diameter are adjusted so as to obtain the predeterminedcharacteristic value under condition that it is wound around a surfaceof the conductive member is attached to a metal article directly, it ispossible to estimate a function for an antenna can be realized.

Also, in the Example 9 and the Example 11 in which a soft magneticmember is disposed further between an aluminum plate or an aluminum filmand the coil main body, it is understood that the L1/L2 value decreasesgreatly with compared to the comparative example 4, and the Q value isimproved with compared to the Example 8 and the Example 10. The higherthe Q value is, the less there is a loss by an eddy current etc. Thus, acharacteristics for the transponder antenna is improved. Therefore, itis understood that a function for the antenna is improved sufficientlyin the present invention in which a soft magnetic member is disposedbetween the conductive member and the coil main body.

Next, an example for showing whether or not the transponder in which anantenna of the present invention is used is actually operable isexplained together with a comparative examples.

EXAMPLE 12

As shown in FIGS. 15 and 16, a coil main body which has 50 mm of outerdiameter and 49 mm of inner diameter is produced by winding a coatedcopper wire which has 0.2 mm of diameter for 4 to 5 times. An aluminumfilm which has a dimension of 60 mm×60 mm and 10 μm thickness isprepared as a conductive member. The coil main body is fixed on asurface of the aluminum film directly, and an IC chip is connected tothe coil main body electrically. Thus, a RFID tag which is a transponderis obtained. An example 12 is such a transponder.

EXAMPLE 13

A coil main body which is the same as that in the example 5 is producedby the same process as that in the example 12. Also, an aluminum filmwhich has the same shape and the same size as that in the example 12 andan acrylic plate which has the same thickness 0.607 mm and the sameouter shape as that of the aluminum film are prepared. The coil mainbody is fixed on a surface of the aluminum film via the acrylic plate,an IC chip is electrically connected to the coil main body. Thus, anRFID tag which is a transponder is obtained. An Example 13 is atransponder in which an aluminum film and the coil main body are fixedtogether so as to have an interval 0.607 mm.

EXAMPLE 14

A coil main body which is the same as that in the example 12 is producedby the same process as that in the example 12. Also, an aluminum filmwhich has the same shape and the same size as that in the example 12. Acircular hole of 40 mm diameter is opened in a center of the aluminumfilm. The coil main body is fixed on a surface of the aluminum film soas to surround the circular hole. An RFID tag which is a transponder isobtained by connecting the IC chip to the coil main body electrically.An Example 14 is a transponder in which the coil main body is fixed onthe aluminum film in which a circular hole is formed.

EXAMPLE 15

A coil main body which is the same as that in the example 12 is producedby the same process as that in the example 12. Also, an aluminum film asa conductive member which has the same shape and the same size as thatin the example 12 and a composite member which includes a carbonyl ironwhich has a dimension of 0.34 mm thickness and outer shape of 60 mm×60mm as a soft magnetic member are prepared. The coil member is fixed on asurface of the aluminum film via the composite member. The IC chip isconnected to the coil main body electrically; thus, an RFID tag which isa transponder is obtained. An example 15 is a transponder a softmagnetic member which is formed in a plate manner is disposed betweenthe conductive member and the coil main body in this way.

EXAMPLE 16

A coil main body which is the same as that in the example 5 is producedby the same process as that in the example 12. Also, an aluminum filmwhich has the same shape and the same size as that in the example 12 isprepared. A paint which includes a flake magnetic powder is applied onan aluminum film and dried: thus, a coating as a soft magnetic memberwith 0.2 mm thickness is formed on a surface of the aluminum film. Thecoil main body is fixed to a surface of the coating. An IC chip isconnected to the coil main body electrically; thus, an RFID tag which isa transponder is obtained. An example 16 is a transponder in which acoating as a soft magnetic member is disposed between the conductivemember and the coil main body in this way.

EXAMPLE 17

A coil main body which is the same as that in the example 12 is producedby the same process as that in the example 12. Also, a composite memberwhich includes a carbonyl iron which has a dimension of 0.34 mmthickness and 60 mm×60 mm outer shape is prepared as a soft magneticmember. A paint which includes a silver powder is applied on a backsurface of the composite member and dried; thus, a coating which has0.15 mm thickness is formed on a back surface of the composite member.Consequently, a coil main body is fixed on a surface of the compositemember. An IC chip is connected to the coil main body electrically;thus, an RFID tag which is a transponder is obtained. An example 17 is atransponder in which a composite member as a soft magnetic member isdisposed between the coating as a conductive member and the coil mainbody in this way.

EXAMPLE 18

A coil main body which is the same as that in the example 12 is producedby the same process as that in the example 12. Also, a coating as aconductive member which has 0.15 mm thickness is formed on a backsurface of the composite member in the same process as that in theexample 10. The coating is removed from the composite member. The coilmain body is fixed on a surface of the coating as a conductive member.An IC chip is connected to the coil main body electrically; thus, anRFID tag which is a transponder is obtained. An example 18 is atransponder which is provided with a coating as a conductive member.

EXAMPLE 19

A coil main body which is the same as that in the example 12 is producedby the same process as that in the example 12. A circular ferrite platewhich has a dimension of 1 mm thickness and 60 mm diameter is preparedas a conductive member. The coil main body is fixed on a surface of theferrite plate directly. An IC chip is connected to the coil main bodyelectrically; thus, an RFID tag which is a transponder is obtained. Anexample 19 is such a transponder.

COMPARATIVE EXAMPLE 4

A coil main body which is the same as that in the example 12 is producedby the same process as that in the example 12. An IC chip is connectedto the coil main body electrically; thus, an RFID tag which is atransponder is obtained. A comparative example 4 is a transponder whichcomprises a coil main body and an IC chip in this way.

COMPARATIVE EXAMPLE 5

A coil main body is produced by winding a coated copper wire which has0.2 mm diameter by ten times around a composite member which includes acarbonyl iron which has a dimension of 1 mm thickness and an outer shapeof 40 mm×40 mm. An IC chip is connected to the coil main bodyelectrically; thus, an RFID tag which is a transponder is obtained. Acomparative example 5 is a transponder which comprises a coil main bodyaccording to a spooling method and an IC chip.

<Comparison Test and Evaluation>

Thickness of the transponders in the examples 12 to 18 are measured andthickness of the transponders in the comparative examples 4 and 5 aremeasured respectively. These transponders are disposed on acrylicplates. L3 value and Q3 value are measured in the coil main body.Consequently, a transmitting/receiving antenna 21 a in an interrogatorwhich is shown in FIG. 22 is accessed by 30 mm; thus, it is confirmedwhether or not it is operable properly.

After that, tags 12 which are shown in FIG. 22 are disposed on steelplates as an article 311 which has 1 mm thickness. L4 value and Q4 valueare measured in the coil main body. Consequently, atransmitting/receiving antenna 21 a in an interrogator is accessed tothese tags 12 under such conditions by 30 mm; thus, it is confirmedwhether or not it is operable properly.

The L3 value, L4 value in the coil main body, measurement result in theQ3 value and the Q4 value, and a result of confirmation of operabilityare shown in a TABLE 5.

TABLE 5 Upper Stage L3(μH) Upper Thick- Lower Stage Q3 Structure of nessStage Lower Transponder (mm) L4(μH) Stage Q4 Operability Example 12Aluminum 0.45 0.541 8.5 Operable Film 0.567 8.8 Operable Example 13Interval to 1.06 1.187 27.7 Operable Aluminum 1.172 27.5 Operable FilmExample 14 Aluminum 0.45 1.127 27.0 Operable Film with 1.067 13.8Operable Circular Hole Example 15 Composite 0.85 1.855 33.1 OperableMember and 1.969 22.0 Operable Aluminum Film Example 16 Magnetic 0.71.754 36.7 Operable Coating and 1.844 36.8 Operable Aluminum FilmExample 17 Composite 0.8 1.790 36.8 Operable Member and 1.8207 36.9Operable Conductive Coating Example 18 Conductive 0.5 0.808 11.4Operable Coating 0.781 12.8 Operable Example 19 Ferrite 1.5 4.611 60.3Operable Plate 4.261 38.9 Operable Comparative Only Coil 0.4 2.968 77.2Operable Example 4 1.213 6.8 Not Operable Comparative Spool 2 4.356 88.4Operable Example 5 mehtod 4.449 60.4 Not Coil Operable

As understood from the TABLE 5, it is understood that variance in both Land Q is large in a case in which a transponder is disposed on a metalmember in the comparative example 5; thus, the transponder which isdisposed on the metal member is not operable properly. Also, in thecomparative example 5, the variance in both L and Q in a case in whichthe transponder is disposed on a metal member is smaller as compared tothe comparative example 2. However, the transponder which is disposed onthe metal member is not operable properly. This is estimated that it iscaused by a fact that a radio wave which is transmitted from atransmitting/receiving antenna in an interrogator which is accessed in adirection which is orthogonal to the metal surface as an article cannotbe transmitted because a direction of a magnetic flux in a so-calledspool method coil is an axial core direction of the coil.

On the other hand, in the examples 12 to 16 which have a conductivemember which is formed by an aluminum film, and in the examples 17 and18 which has a conductive member which is formed by a conductivecoating, both the L value and Q value are relatively small. However,their variances are small; thus, it is understood that the transponderin a case in which it is disposed on a metal member is operableproperly. Consequently, with compared to the embodiment 12 in which acoil body is fixed on an aluminum film directly, it is understood thatboth the L value and the Q value are improved in the example 13 in whichan interval is disposed and the example 14 in which a circular hole isformed on an aluminum film. In addition, it is understood that both theL value and the Q value are improved in the examples 15 to 17 in which asoft magnetic member is disposed between the conductive member and thecoil main body. Therefore, it is understood that the function for theantenna can be improved sufficiently in the present invention in which asoft magnetic member is disposed between the conductive member and thecoil main body.

Also, it is understood that both the L value and Q value are improvedfurther in the example 19 in which the coil main body is fixed on asurface of a ferrite plate which is a soft magnetic member; thus, atransponder it self is operable properly. Therefore, it is understoodthat a predetermined characteristic value can be obtained reliably andoperable properly even if the transponder is attached on a surface of ametal article as long as the predetermined characteristic value can beobtained only by blocking the magnetic force from the soft magneticmember.

INDUSTRIAL APPLICABILITY

As explained above, according to the present invention, a magnetic coremember which is inserted into an air-core coil is formed by a compositemember which is rigid with compared to a magnetic core member which isformed by a fragile ferrite sintered member such that the magnetic coremember is approximately parallel with a plane in an air-core coil whichis wound helically in a plane. Therefore, it is possible to enhance therigidity of an antenna coil. Also, a composite member which forms themagnetic core member is dispersed in a soft magnetic metal member, or aplastic or a rubber in which a powder or a flake of amorphous or aferrite. The powder or a flake are insulated mutually, an entiremagnetic core member does not have a conductivity. Therefore, an eddycurrent is not generated even if it receives a high frequency radiowave. Therefore, it never occurs that the Q value decreases due to thegeneration of the eddy current even though the radio wave has arelatively high frequency. Thus, it is possible to obtain an antennacoil which can be used sufficiently in a relatively high frequency.

Also, it is possible to form a magnetic core member relatively thinly byforming the magnetic core member by performing an injection moldingoperation, a compressing molding operation, or post-flattening moldingoperation for the composite member. It is possible to obtain a magneticcore member which has 0.8 mm or thinner thickness which has beendifficult to form in an injection molding operation or compressingmolding operation if a magnetic coating which is formed by applying anddrying a composite member as a magnetic core member is used. As aresult, it is possible to restrict a protruding amount of the antennacoil from the article greatly if it is attached to an article.

Furthermore, if a non-magnetic conductive plate which has a conductivityis layered on a surface of an air-core coil in which a magnetic coremember is inserted, the conductive plate block the radio wave toward thearticle. Therefore, a space which is supposed to be inserted between anantenna coil and an article is not necessary. Thus, it is possible tooperate the antenna coil reliably under condition that a protrudingamount of the antenna coil from an article which is an object to becontrolled is reduced than a conventional case.

In addition, the present invention comprises an insulating member,continuous conductive members in which forwarding sections and returningsections are formed alternatively so as to wind on a surface of theinsulating member, and a first magnetic core member which is bonded on aback surface of the insulating member. Therefore, a magnetic flux whichis generated by an electric current which passes the conductive memberis parallel with a surface of an article on which an antenna coil isattached after passing the first magnetic core member. Also, the firstmagnetic core member is bonded on a back surface of the insulatingmember so as to cover the returning sections from a back surface of theinsulating member without overlapping the forwarding section. A part ofthe magnetic flux which passes through the first magnetic core member isdispersed in its end section so as to pass above the forwarding sectionsand return to the neighboring first magnetic core member again. Thus, itis possible to operate reliably without receiving an influence even if asurface of an article is a metal member.

Also, if the second magnetic core member is bonded on a surface of theinsulating member so as to cover the forwarding sections and overlap anend section of the first magnetic core member to which the end sectionneighbors without overlapping the returning sections, the magnetic fluxpasses through the first magnetic core member and the second magneticcore member while moving between the first magnetic core member and thesecond magnetic core member alternatively. Therefore, the forwardingsections and the returning sections exist on a top surface and a backsurface of the magnetic flux alternatively; thus, the continuousconductive member which includes the forwarding sections and thereturning sections is formed unitarily with the antenna coil which iswound around the magnetic flux. Thus, it is possible to obtain anantenna coil relatively easily which has the same characteristics asthose in a conventional antenna coil which has been produced by windinga lead wire around an outer surface of the magnetic core member. Thus,it is possible to improve the productivity in a mass production.Furthermore, if a continuous conductive member is formed by a pluralityof lead wires which are formed so as to wind on a surface of theinsulating member with a predetermined interval along with each other,it is possible to increase so called a turning number easily byincreasing the quantity of the forwarding sections and the returningsections which exist on a top surface and a back surface of the magneticflux. By increasing the turning number, it is possible to improve thecharacteristics of the antenna coil.

Furthermore, if it is formed by performing an etching operation, apunching operation, a screen printing operation, or a vapor depositionoperation of the conductive member, it is possible to form a conductivemember on an insulating member relatively easily. If the first magneticcore member or the second magnetic core member is a soft magnetic metalmember, a composite member of a powder or a flake and a plastic whichare made of an amorphous or a ferrite, a plate or a film of a softmagnetic metal member, an amorphous film or its layered member, or aferrite, the magnetic core member is relatively thin. Thus, it ispossible to form an entire thickness of the antenna coil thinly. Inparticular, by forming a magnetic core member by a magnetic coating, itis possible to form the magnetic core member further thinly; thus, it ispossible to obtain a further thin antenna coil by a magnetic core memberwhich has 0.8 mm thickness which has been difficult in an injectionmolding operation.

Furthermore, the present invention comprises a coil main body which ismade of a conductive member which is wound helically in a plane and amagnetic core member in a plate manner or a sheet manner which is bondedon a surface of the coil main body such that an end section ispositioned in a central part which is surrounded by the coil main bodyso as to cross a part of the coil main body and the other end ispositioned outside the coil main body. Therefore, it is possible toenhance the Q value while maintaining such a thin thickness of theantenna coil. Also, the magnetic flux which is generated by an electriccurrent which passes toward the coil main body which is formed by aconductive member passes through the magnetic core member such that itsmagnetic flux direction is parallel with a surface of an article. Aneddy current which is generated in a metal on a surface of the articleis restricted even if the tag antenna coil is attached on a surfacewhich is formed by a metal of the article. Thus, it is possible toobtain an antenna coil which can be operated reliably even if it iscontacted closely on the metal article.

Also, a coil main body is formed by winding a conductive member 211helically around a main surface of the electrically insulating film or asheet, and a magnetic core member is layered on another main surface. Bydoing this, it is possible to obtain an antenna coil by relatively easyoperation and improve the productivity in the mass production withcompared to a conventional antenna coil shown in FIG. 23 which has beenformed by winding a lead wire on an outer surface of the magnetic coremember. Consequently, if a magnetic core member is formed by applyingand drying an ink or a paint which include a magnetic powder on anothermain surface of an electrically insulating film or a sheet, it ispossible to obtain a magnetic core member which has 0.8 mm thickness orthinner which has been difficult to form in an injection moldingoperation and a compressing molding operation and form the thickness ofthe antenna coil very thinly. Therefore, it is possible to restrict theprotrusion of the antenna coil from the article greatly if it isattached to an article.

Furthermore, if the magnetic core member is disposed so as to be a nearsection for contacting the article, the magnetic flux which is generatedby an electric current which passes toward the coil main body passesthrough mainly the magnetic core member; thus, few of the magnetic fluxpasses the article. Also, if a conductive member in a sheet manner or aplate manner is bonded on a surface of the coil main body so as to coverthe magnetic core member, the conductive member is disposed between thecoil main body which is formed by a conductive member and the article.Therefore, a radio wave is blocked toward the article by the conductivemember. By doing this, if a surface of the article is formed by a metal,a loss is not generated by an eddy current etc. which is generated on ametal surface. As a result, it is possible to operate the antenna coilreliably.

In addition to the above explanations, the present invention comprises aconductive member which is formed in a plate manner such that a backsurface of the conductive member is attached to an article and a coilmain body of which turning number or a turning diameter is adjusted soas to obtain a predetermined characteristic value under condition thatit is wound and fixed helically on a plane of the conductive memberdirectly or with a predetermined interval. Therefore, it does not occurthat the characteristic value of the coil main body varies greatly evenif this antenna is attached to a metal article which is an object to becontrolled. Thus, a space which has been necessary for attaching theantenna on a metal product conventionally is not necessary. Thus, it ispossible to avoid the protrusion of the transponder from an articlewhich is an object to be controlled greatly.

Also, if a soft magnetic member is disposed between a conductive memberand the coil main body, the coil main body is blockedelectromagnetically from the conductive member by the soft magneticmember; thus, the Q value of the coil main body improves. Therefore, itis possible to adjust the turning number and the turning diameter of thecoil main body so as to obtain a predetermined characteristic valuerelatively easily. Also, it is possible to obtain a predeterminedcharacteristic value even if this antenna is attached on a surface of anarticle which is made of a metal.

Furthermore, if a back surface of the soft magnetic member on an articleand the coil main body which is wound helically is fixed on a surface ofthe soft magnetic member directly or with a predetermined interval, theradio wave toward the metal part is blocked by the soft magnetic memberwhen a radio wave is transmitted under condition that an antenna isattached to an article which is made of a metal. Therefore, an eddycurrent is not generated in its metal part. As a result of this, a spacewhich has been necessary is not necessary even if an article is made ofa metal; thus, it is possible to prevent the antenna from contactingmembers therearound while being transported.

1. An antenna coil comprising: an air-core coil formed by a coil memberwound on a plane; and a magnetic core member inserted in the air-corecoil to be approximately parallel to the plane in the air-core coilwherein the magnetic core member is formed by a composite memberincluding, a soft magnetic metal member, one of a powder of an amorphousmember, and a powder of a ferrite member, and one of a plastic memberand a rubber.
 2. An antenna coil according to claim 1, wherein themagnetic core member is formed by at least one of the steps of: ejectingthe composite member; compressing the composite member; and re-shaping aflat rolled composite member.
 3. An antenna coil according to claim 1wherein the magnetic core member is formed by a magnetic coating whichis formed by drying the composite after applying the composite.
 4. Anantenna coil comprising: an air-core coil formed by a coil member woundon a plane; and a magnetic core member inserted in the air-core coil tobe approximately parallel to the plane in the air-core coil, wherein anon-magnetic conductive plate is layered on a surface of the air-corecoil through which the magnetic core member is inserted.
 5. An antennacoil according to claim 4 wherein the conductive plate is formed by acopper, a copper alloy, an aluminum, or an aluminum alloy.
 6. An antennacoil according to claim 5 wherein the conductive plate has 0.01 to 2 mmthickness.
 7. An antenna coil comprising: an insulating member formed byan electrically insulating film or an electrically insulating sheet; acontinuous conductive member including forwarding sections and returningsections formed alternatively to wind on a surface of the insulatingmember; a first magnetic core member bonded on a back surface of theinsulating member to cover the returning sections from the back surfaceof the insulating member without overlapping the forwarding sections. 8.An antenna coil according to claim 7 wherein: a second magnetic coremember covers the forwarding sections ot to overlap the returningsections on the surface of the insulating member such that an endsection of the second magnetic core member is bonded to overlap an endsection of the first neighboring magnetic member; and the secondmagnetic core member introduces a magnetic flux which passes through thefirst magnetic core member onto a surface of the insulating member onthe forwarding sections.
 9. An antenna coil according to claim 8wherein: a plurality of conductive lines are disposed to wind on asurface of the insulating member in a predetermined interval along witheach other in the continuous conductive member; and wherein an endsection of the conductive line is connected to a starting end section ofthe neighboring conductive line.
 10. An antenna coil according to claim7 wherein: a plurality of conductive lines are disposed to wind on asurface of the insulating member in a predetermined interval along witheach other in the continuous conductive member; and an end section ofthe conductive line is connected to a starting end section of theneighboring conductive line.
 11. An antenna coil according to claim 7wherein the continuous conductive member is formed on a surface of theinsulating member by: etching a conductive film which is bonded on anentire surface of the insulating member in a predetermined pattern; orperforming a screen printing operation or a vapor deposition operationof the conductive member on a surface of the insulating member in apredetermined pattern.
 12. An antenna coil according to claim 7 whereineither one or both of the first magnetic core member or the magneticcore member is formed by a soft magnetic metal member, a powder or aflake which is formed by an amorphous member or a ferrite member, aplastic composite member, a plate or a film which is formed by a softmagnetic metal member, an amorphous film or its layered member, or aferrite member.
 13. An antenna coil according to claim 7 wherein eitherone or both of the first magnetic core member and the magnetic coremember is formed by a magnetic coating which is formed by applying anink or an applying member which include a magnetic powder onto theinsulating member and drying the ink or the applying member.
 14. Anantenna coil according to claim 7 wherein a conductive member made of asheet member or a plate member is bonded onto a back surface of theinsulating member to cover the first magnetic core member.
 15. A tagantenna coil comprising: a coil main body formed by a conductive coilmember wound in a plane; and a magnetic core member made of a sheetmember or a plate member bonded on a surface of the coil main body suchthat an end of the magnetic core member is disposed in a central sectionwhich is surrounded by the coil main body and another end of themagnetic core member is disposed at an outside of the coil main body tocross a part of the coil main body.
 16. A tag antenna coil according toclaim 15 wherein the coil main body is formed by punching a conductiveplate or a conductive film.
 17. A tag antenna coil according to claim 15wherein the coil main body is formed by: etching a conductive film whichis bonded on an entire main surface of an electrically insulating filmor a sheet in a predetermined pattern; or performing a screen printingoperation or a vapor deposition operation of the conductive member on anentire main surface of the electrically insulating film or the sheet ina predetermined pattern.
 18. A tag antenna coil according to claim 17wherein the magnetic core member is a magnetic coating which is formedby applying an ink or an applying member which include a magnetic powderonto another main surface of the electrically insulating film or a sheetand drying the ink or the applying member.
 19. A tag antenna coilaccording to claim 15 wherein the magnetic core member is a magneticcoating which is formed by applying a soft magnetic metal member, apowder or a flake which is formed by an amorphous member or a ferritemember, a plastic composite member, a plate or a film which is formed bya soft magnetic metal member, an amorphous film or its layered member,or a ferrite member, or an ink or an applying member which include amagnetic powder onto an electrically insulating film or a sheet anddrying the ink or the applying member.
 20. A tag antenna coil accordingto claim 15 wherein a conductive member made of a sheet member or aplate member is bonded onto a surface of the coil main body to cover themagnetic core member.
 21. An RFID tag comprising: an antenna coilattached to an article according to claim 15; and an IC chip connectedto the antenna coil electrically such that a specific information foreach article is stored in the IC chip, wherein the antenna coil isattached to the article such that the magnetic core member is disposedbetween the article and the coil main body.
 22. A transponder antennaconnected to an IC chip or a condenser electrically to be attached to anarticle comprising: a conductive member having a back surface attachedto the article; and a coil main body wound helically on a surface of theconductive member via an insulating member and fixed thereon such that aturning number and a coil diameter are adjusted to realize apredetermined characteristic value under a wound condition, wherein anelectric resistance for a portion of the conductive member having 1 cmwidth and 1 cm length is 5Ω or lower.
 23. A transponder antennaaccording to claim 22 wherein the conductive member is a conductivemember which is formed by connecting both ends of a sheet, a plate, afilm or a coil.
 24. A transponder antenna according to claim 22 wherein:the insulating member is a non-conductive sheet, plate, or film; theconductive member is a conductive coating which is formed by applying aconductive ink onto a back surface of the insulating member and dryingthe conductive ink; and the coil main body is wound around a surface ofthe insulating member to be fixed therearound.
 25. A transponder antennaaccording to claim 24 wherein an interval between the conductive memberand the coil main body is 0.01 to 5 mm.
 26. A transponder antennaaccording to claim 22 wherein: the conductive member is formed bylayering a conductive plating layer or vapor deposition layer on a backsurface of the non-conductive sheet, plate, or a film; and the coil mainbody is wound around a surface of the sheet, a plate, or a film so as tobe fixed therearound.
 27. A transponder antenna according to claim 22wherein a hole is formed on a section which is surrounded by the coilmain body of the conductive member.
 28. A transponder antenna connectedto an IC chip or a condenser electrically to be attached to an articlecomprising: a conductive member having a back surface attached to thearticle; and a coil main body wound helically on a surface of theconductive member via an insulating member and fixed thereon such that aturning number and a coil diameter are adjusted to realize apredetermined characteristic value under a wound condition, wherein asoft magnetic member is disposed between the conductive member and thecoil main body.
 29. A transponder antenna according to claim 28 whereina product of a transmission rate of the soft magnetic member and athickness represented in a unit such as mm indicates 0.5 or larger. 30.A transponder antenna according to claim 28 wherein the soft magneticmember is formed by any one of members of an amorphous alloy, aPermalloy, a magnetic steel, a silicon steel, a sendust alloy, a quenchsolidified member for Fe—Al alloy or a soft magnetic ferrite, a castedmember, a rolled strip member, a forged member, or a sintered member.31. A transponder antenna according to claim 28, wherein the softmagnetic member is at least one of: a composite member of at least oneof soft magnetic metal powder, soft magnetic metal flake, soft magneticferrite powder, and soft magnetic ferrite flake, and at least one of aplastic member and rubber; and a coating of an applying member includingat least one of soft magnetic metal powder, soft magnetic metal flake,soft magnetic ferrite powder, and soft magnetic ferrite flake.
 32. Atransponder antenna according to claim 28 wherein the soft magneticmember is a sheet which is formed by bonding a plurality of flakes whichare made of a soft magnetic metal member or a soft magnetic ferrite ontoa surface of a plastic base sheet such that the flakes contact closelyeach other.
 33. A transponder antenna according to claim 28 wherein thesoft magnetic member is a sheet which is formed by: bonding a pluralityof flakes which are made of a soft magnetic metal member or a softmagnetic ferrite onto a surface of a plastic base sheet such that theflakes contact closely each other; covering the flakes by a plasticcover sheet; and attaching the base sheet and the cover sheet.
 34. Atransponder antenna attached to an article connected to an IC chip or acondenser electrically comprising: a soft magnetic member formed in asheet manner having a back surface directly attached on the article; anda coil main body wound helically on a surface of the soft magneticmember to be fixed thereon such that a turning number and a coildiameter are adjusted to realize a predetermined characteristic valueunder a wound condition.